A pretty compelling one is this strip, where Calvin had no opportunity to take the cookies without Susie noticing: I also find it interesting that "real" Hobbes appears in the second pane.
Then there's this one, where Calvin would probably have some serious difficulty getting that high up a tree while holding a water balloon on his own, but more convincingly, Calvin is shown leaving the water balloon at the base of the tree before he climbs:
There's also a few where it's unlikely Calvin did something.
There's the tied up one in the OP, for example.
There's also this one, where Hobbes probably stole a piece of cake:
There's this one, too, which, assuming it happened as shown, would be very strange if Hobbes wasn't involved: There's some honorable mentions as well, although I didn't feel they were strong enough to explicitly mention above.
They hint at things done by Hobbes to Calvin but one could imagine Calvin doing them to himself:
Hobbes knocking Calvin backwards at the door Hobbes throwing a water balloon at Calvin, and dragging a full kiddie pool Hobbes makes a clay tiger at the same time that Calvin makes a clay bowl, and Hobbes' is much higher quality Hobbes carries Calvin on his shoulder and puts him in a tree, then tickles his feet Hobbes places Calvin in a large rain barrel, and Calvin appears to not be happy about it
There's a lot of other examples along these lines if you look around
( this is a good source , for example).
But Watterson left it intentionally vague, so as with all questions related to Hobbes' existence, we can never be 100% sure.
scifi.stackexchange.com/users/23051/Jason C
No.
In the examples provided, as well as every other strip that I can find, there'snothing inconsistent with a young child who has a very vivid imagination.
My personal opinion is that when Hobbes does many of the things that Calvin credits(or blames) him for, Calvin is actually pretending that he's Hobbes.
The issue in the comic strips is that, when we see the "living" Hobbes, we'reeither seeing the other reality that nobody else sees (in which case Hobbesreally is alive and is Calvin's active co-conspirator), or we're inside Calvin's imagination,in which case, how much of the rest of the scene is also his imagination?
Note that the fact that it's his imagination doesn't make it any less real, but it's a subjective reality, rather than an objective one.
We don't know that Calvin didn't have the opportunity to take the cookies; hecould just be very very sneaky.
I've watched children, while pretending, do things equally as elaborate to setup a simple scenario and then maintain that their imaginary friend helped them,they "flew up here," or given any of a dozen other explanations.
Again - ifHobbes is real, then he helped.
If Hobbes is pretend, then what else ispretend in the scene?
Simple deflection.
Who's to say that Calvin didn't sneak in for a piece ofcake earlier and then pretend (even to himself)
that Hobbes did it.
Somebody else commented that this could just be an elaborate explanation fora wipeout.
Makes sense.
Rationalization for falling down, or what he imagined (wished?)
would happento Suzy.
scifi.stackexchange.com/users/28471/Doug R.
In the following cartoon strip Hobbes presses the button on the outside of Calvin's Duplicator .
Given the position of the button, there's simply no way that Calvin could have pushed it himself, from inside the machine.
scifi.stackexchange.com/users/20774/Valorum
Eating Tommy Chesnutt: Calvin could not have eaten his classmate.
scifi.stackexchange.com/users/59810/Wildcard
Yes.
Hobbes unlocks the front door of the house and leaves without Calvin's mom noticing.
Notice
the last panel - Calvin sneaks home from school and does not enter the house, as evidenced that his mother has not yet noticed him.
It is strongly implied from the wording as well that Calvin has just arrived back from school and has not yet entered the house.
Yet, HOBBES IS OUTSIDE .
scifi.stackexchange.com/users/89771/TheAsh
So  this question  got me thinking that, except for pure Calvin fantasy (i.e. Spaceman Spiff, where nothing is real), is there ever a comic where Calvin claims Hobbes did something and Calvin could not have possibly performed himself? This one comes close, but Calvin could have tied himself up   Note that we don't have to see Hobbes having done it, just that it would have very difficult or impossible for Calvin to have done it.
Does Hobbes ever do anything that Calvin himself could not do?
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<comics><calvin-and-hobbes>
scifi.stackexchange.com/questions/156596
scifi.stackexchange.com/users/62709/Machavity
There are few examples of instances in which Hobbes has done something which Calvin himself could not do. The OP's example of Calvin being tied up is one such example. Other examples include eating Tommy Chesnutt and Hobbes unlocking the front door without Calvin's mum noticing. Finally, there is the instance in which Hobbes presses a button on the outside of Calvin's duplicator. There are many strips where it can appear certain that Hobbes is doing things that Calvin could not have done - but Watterson always leaves an element of uncertainty so the reader can never be 100% sure.
Here are a number of strips providing compelling  evidence that Calvin is not doing the stuff that he says Hobbes does. At the same time, Watterson is careful never to provide 100% evidence - there is always an element of uncertainty. All of the strips can be explained as the product of a child's imagination - Watterson is simply playing with the POV. In the cartoon presented here Hobbes is pressing a button which would be physically impossible for Calvin to press due to its position. Calvin could not have eaten his classmate Tommy Chesnutt. Yes - in a strip where Hobbes leaves the house by himself before Calvin entered after returning from school.