It's polite to flush after using the restroom.
Randy is using the restroom at the gym and notices the flush handle appears to be quite dirty.
Randy wants to avoid touching the handle.
Randy uses his foot on the flush handle to press it down.
Randy leaves after using the restroom and does not flush it.
The next person to use the bathroom has more a sanitary facility to use.
The person that uses the restroom after Randy is grossed out that someone didn't flush.