Their middle name.
They share the same middle name.
steer clear
the pirate replied, "Arrg it's driving me nuts!"
Gomer's Pile
For me, it's gotta be Emo Phillips' Baptist joke. Although to tell it you've gotta get his execution down.
They both ate honey and they both have the same middle name.
Atilla the Hungry.
An army of Hun-dread.
The same middle name.