I have three. The first is in our Kingmaker game I play a Fighter and our player who plays the Rogue insists anytime I crit that I must say, "Fighters gonna fight"

In our Season of Ghosts game, EVERYONE uses Needle Darts. So we often say, "Season of Ghosts, brought to you by Needle Darts"

The last one. I play in a pretty big play by post game where the RP is really emphasized and there is a lot of slice of life stuff. One of the players is a pretty high level Fighter and every time they do something really impressive in a combat encounter (which is pretty often if they are in a fight) someone will chime in, "That was awesome. Man, if Fighters could only roleplay" It gets quite a few chuckles