sparrow's nest
A slang term for the anus. Whereas "into the cuckoo's nest" pertains to vaginal sex with a female, "into the sparrow's nest" pertains to anal sex. In this context, it is often used as a boast, as entering the cuckoo's nest generally requires less effort to achieve. It can also be used to describe a homosexual man, who elects to persue the sparrow's nest on all counts, and has no interest whatsoever in the cuckoo's nest.
"Damn, that girl was dirty. After one night together she let me flip her over and make a beeline straight for the sparrow's nest."
"Jeff? No, he won't want to come out with us to the club tonight. He'll be off out on the other side of town with Percy and Rupert to chase some sparrow's nest."
"Jeff? No, he won't want to come out with us to the club tonight. He'll be off out on the other side of town with Percy and Rupert to chase some sparrow's nest."