Alex and his sense of humor!

ALREADY?  At only 2 years old, my son is a bit on the sarcastic side.  He has a way of expressing almost adult like dry humor.  The other day we were at my dad's house.  He began twirling himself around and then acting like he was dizzy and falling flat to the ground.  He gained so many laughs that he continued to do it.  Today, he was running around and kissing things saying, "Mommy kiss, baby kiss, etc."  He got to Elmo and made one Elmo kiss the other.  He then began to say, "Oooooo...Elmo kiss Elmo."  He is so funny and I swear I am not just saying that because he is my son.  I think I would be great friends with him if he wasn't my boy!  When did he become so funny?  How do they learn these things?  Is is innate?  Was Jerry Seinfeld a funny little boy?  Who knows!  I can't wait to see what he does next!