I came up with so many replies to this post that I couldn't make up my mind which one was best, so here is a list of the top five.
1) Gee Sling, did you come up with that one all by yourself?
2) Monkey see... Monkey do...
3) It was only funny when I did it.
4) Mimicry is the most sincere form of flattery.
5) I'm stunned by your witty retort. <I'm not worthy, I'm not worthy...>