Butt stuff???

So the guy I’ve been with pretty regularly now for about a month asked me something strange the other day.

I’m not super adventurous in the bed room but

am open to learn and try new things but while I was giving him a blow job he asked me to put a finger in his butt😳

I have never done that before (clearly) and don’t know how to even do that to make it pleasurable for him😅

any advice 😅

Clarification: this guy is an ex of mine from way back but we’ve recently rekindled our relationship and have been pretty steady and serious for about a month, sorry for the confusion. We are very comfortable around each other and it is truly a no judgement zone. I just want to please him but don’t exactly know how😅😅