a finger in the bum
When someone yells this at you like a madman, it usually means they want to know what you like doing when you're getting it on.
My dad yelled it at me after I asked if he wanted to join my Zoom call with my girlfriend.
My brother said it at me when I told him I had a new girlfriend.
My friend shouted it at me when I asked if he wanted to try a new app for dating.