I'm proud to say that I'm naturally a pervert, so being 'sexual' is easy for me because, well, everything's sexual to me. But, I'm not always the most creative person in the world, so I borrow other people's lines. Typically, I borrow them from music or movies. What I've done is identify bands that have sexual lyrics or a sense of humor...usually these are one in the same. Here is the list of the bands that I have actively stolen from:
She Wants Revenge (Sexual, passionate)
Mickey Avalon (Sexual, funny)
The Bloodhound Gang (Sexual, funny)
And, unknown to me at the time, Dane Cook
There are a handful of others, but these three artists are the ones that I have 'stolen' from the most. Don't worry about getting called out for using someone else's material (unless it's a very similar bit from a comedian, which in that one isolated case didn't hurt me at all), the fact is that most people A) have never heard the lyric/line you're quoting or B) cannot, consciencely, process the lyric/line you're using as being unoriginal, or borrowed, because conversations move so quickly.
Also, if you DO get called out for using someone else's material, more than likely the fact that you both have a common interest in an artist works to build a bridge towards comfort and, ultimately, sex.