I'm not funny, I suck at any form of banter.

Example My usual suspects out back drinking, one (in good spirit) out of nowhere comes at me with "Lava, ayo lava" "Sup" "You're a bitch." I can't think of a response

I can write for days, years of being into rap music has allowed me to learn to freestyle yet simple conversation I can not do.

How do I approach this?