The sound of someone taking their shoes and socks off.
Johnny wanted to sniff his bare feet, so he took off his shoes and socks with a "Ch Ch Ssssss Ssssss."
(UK Slang) Rough anal sex performed by gay men.
Auntie Lee got suspended from his job as a steward after being heard in the toilet having a bit of rumpy-dumpy with one of the passengers by almost everyone on the flight. He's been a mummy's boy on jobseeker's ever since.