what do I say?

I was talking to my cousin online, but I barely know him.
Anyway, he was talking about breakdancing, which I don't exactly know anything about.
I end up replying pretty much the same thing:
"That's awesome!"
"That's cool!"
"Sweet!!"
It really got really irritating.
I know I hate it when other people reply to me that way,
but I'm just so lost as to what to say.
Our conversation became way too boring, so I just logged off.
Sometimes I just wish he'd stop talking to me;
I just feel too pressured to think of something to say.
I know this sounds ridiculous, but it'd be so much easier for me if he stopped talking to me. =/