prankster
cut-up
trickster
tricker
hoaxer ,
practical joker

That should cover it, unless some other practical joker had been at the robot's memory.

And then, basically, everybody's always told me that he was a really big practical joker.

He was also known for his sense of humor and as a practical joker.

I never really figured her for a practical joker, but this is a good one.

He is a practical joker and is dead serious about his job.

One may say the type of practical joker, for these people are exactly alike all over the world.

A practical joker who takes risks like that has to be taken seriously.

It doesn't seem like the work of a practical joker.

"What about some practical joker with a set of fake feet?"

They were notorious practical jokers, and she wouldn't put anything past them.