What is an R.J. in sex?

[AnAnimalLoverNamedShelbie]

My friend Trevor said something about an R.J. in sex. I can't figure out what it means! No other sites tell you! Could you help me?
I know what a b.j. is but not an r.j.
Please tell me!

 

[Mr. Scrotum ♥S you!]

ask trevor to show you since he told you about it.

trevor is hotttttttttttttttttttttttttttttttt.

 

[nocturnae]

rim job was my guess too

 

[Elle]

Rim job?