There are several running gags/inside jokes on the show.
impractical Jokers Running Gags:
- "Larry" is a fake name frequently used by Joe when having to search for someone/get someone
-"Moustache" is a nickname originally used by Q. The person who was nicknamed did not take it well and now whenever the jokers come into contact with someone with a moustache, they're asked to refer to them as 'moustache'
-In the episode "Permanent Punishment", Joe punished Sal, Murr and Q by making them have tattoos which he designed. Q's was "38. Lives Alone. Has 3 cats.", Sal's was a tattoo of Jaden Smith and Murr's was a ferret skydiving. Since the episode, the tattoos have been referenced and seen several times.
-Murr's fear of skydiving. He was punished by having to skydive in 'Look out Below' and since the skydive has been referenced in a couple of episodes. It is also what his tattoo of a ferret skydiving references.
-Sal's fear of germs.
-"Up Your Ass and to the Left" though more recent and only mentioned a couple of times on air, this is a known inside joke between the guys on the show.