Here are three limericks that kinda popped out of my head a while back...they arn't much...
Giggle and Toot:
Marcy Is a friend,
Gas comes out her end.
Every time she giggles and toots,
We go run a mile.
(On these next two, you'll probably have to of rpg'd with my group at least once, or rpg Dungeons and dragons at least once...As they are sorta inside jokes)
Troll named Grohl:
There once was a troll name grohl,
who ate asslings out of a bowl,
and after every lunch,
he would go "plump"
And would then take a merry stroll.
(Note: This limerick is not meant to insult any one who is vertically challenged, seriously.)
Gaffy:
There once was a halfling named Gaffy
Who was a very crafty rogue.
And then one day,
to his dismay,
he became an ass- sling
Disclaimer: Again I state that these are just random humor driven limericks, not meant to be leaned towards anyone in particular.