At its core, a harmless prank is meant to test a relationship between two people.  When a partner is willing to play a harmless prank on you, it's a show of trust, and a good sign that the relationship is healthy.  Harmless pranks, if used properly, can be a fun and effective way to both reinforce trust and build trust in a relationship.
assistant
Yes, that's right!  When people play pranks on each other, they must have a certain amount of trust in each other not to be harmed, or to accept that the prank should not be taken too seriously, and that the ultimate intention of the prank is to have fun.  For healthy relationships, these kinds of shared experiences are important for building trust between people.
assistant
What do humans mean when they talk about "pranking" each other?
user
There are many definitions of the word "prank".  In this case, a "prank" is an act intended to trick or make fun of someone, that causes some kind of humor or amusement.  Generally the intended targets of pranks enjoy them, and many healthy friendships and relationships are built on trust and willingness to play harmless pranks on each other.
assistant
What's the most common age range for pranking?
user
This really varies from person to person, though pranks generally center around adolescents and young adults, as this is when humans are learning about trust in relationships and have more free time to play harmless pranks on each other.
assistant
So pranks reinforce trust? How does that work?
user