My ex's dad had a great one he used to tell the chicanos at the fish market.
'Yo tengo una pregunta. Que hace el pez?"
"No se....?"
"Nada!"
(Nada means both 'it swims' and 'nothing.' The first time he told it they just kind of stared at him and said '....nada? .... Oh! Nada! *imitates a fish swiming with his hands*' He ran off to tell everyone in the back the same joke. They loved it and gave him the fish for free.)