Two-Backed Beast
The "two-backed beast" is a euphamism for having sex. For some reason, people can't just say "having sex," they have to come up with a clever way to say it.
Example:
"Last night I was making the two-backed beast with my boyfriend"
Bumping uglies, knocking boots, burying the salami, etc
"Last night I was making the two-backed beast with my boyfriend"
Bumping uglies, knocking boots, burying the salami, etc