orgasm
if you don’t know this one, then you definitely need JanesGuide!
OTC
you’ll sometimes see this used in reviews to denote “one time charge” – a site that offers a single month (or other term) access without automatically renewing/billing you.
Otter
slang for a gay man who is very hairy, but too small (in frame size) to be called a bear.
over the knee, OTK
spanking done with the recipient bent over the spanker’s lap, often done in corporal punishment and/or family play scenes