I actually used a limerick in a game once, and will post it at the end of this story.
It was a White Wolf munchkinny one-shot, in which I played an Eshu (a satyr-like bardlike faerie), my brother played a were-spider, one friend played a wizard, and another friend played a werewolf. My PC's goal was to slay the firebreathing dragon that had killed his family.
To inspire the party when we went on our quest, I recited the following limerick:
A wolf, and a mage, and a spider,
and a fae sought a wyrm -- not to fight her,
for she'd make lousy sport --
but in any fae court,
she'd be such a chic cigarette lighter.
Thank you, thank you, I'll be here all night.
Daniel