This is a street in Los Angeles. But more importantly, cahuenga is synonymous for wang, sausage, shlong, cock, etc. A further constraint on the word, it is only used when describing a particularly large member.
A girl describes a hot night she spent with some guy, as she spills the juicy details she remarks, with a HUGE grin on her face, "yeah it was amazing, he had the hardest cahuenga and he knows how to work it..."
Girl #1: Did you see her all over that gay boy last night?
Girl #2: I'm afraid that I didn't. How did she pull that off?
Girl #1: Well let me tell you. Both of those bitches were on Cahuenga!