Sweating up a storm
When the weather is so hot (or you are aroused, but usually hot) that you sweat a lot.
Boy: Gee, it's hot out there!
Girl: I know, I'm sweating up a storm!
Girl: I know, I'm sweating up a storm!
sweat it up
Make the situation (sometimes uncomfortably) hot and heavy.
A: Hey Tyrese, the 80's called and they'd like their garish tight cycling shorts back.
T: (humps A's leg) Don't be so frigid Alexandrei, SWEAT IT UP
T: (humps A's leg) Don't be so frigid Alexandrei, SWEAT IT UP