When you go to take a poop and you push so hard and clench your jaw so hard your toes begin to sweat.
Or
Referring to a sexual moment when performing anal sex on the receving end, you clench your jaw and toes so hard they begin to sweat
Man i got sweaty toes real bad after eating that lasagna.
I gave Jessica sweaty toes last night.
I can’t believe that George gave me sweaty toes last night.