Alongside dudu this is a non-vulgar kidtalk way of saying penis in maltese, however can it also refer to a small penis. I.e. a pecker Maltese people also use this word to call each other wimps.
"Qed nibza mmur mal-mara ax qadt ma hxejt ghadni" (I'm scared of making love to my wife because i've never fucked yet.)
"hahah. Ja Pexixa" (Hahah. You wimp.)
"Mummy int ghandek pexixa?" (Mummy do you have a dick?)