When either extremely drunk, or just plain tired, and you fall asleep whilst engaging in intercourse with your significant other.
Person 1: "Hey Brochacho, why looking so glum?"
Person 2: "Been working doubles all week and was so tired last night I caught a snooze in the tuna. Shit left me with the bluest of balls!"
Sweaties are not the rarest of breeds and should be approached with extreme caution and with plenty of deliberation between you and your drinking buddies for the evening. These aggressive ladies are often found in groups, scantily clad, and sweating profusely from the molly and hours of uncoordinated dancing. Though they are very overweight and most likely dehydrated, do not let that fool you. Once a sweaty has lured you in, they cannot be left behind. She can be driving an early 90's honda hatchback yet she is still going to be right on the tail of your brand new Tesla. If you do manage to break line of sight then they began employing primitive yet effective tracking methods.
Steve Jobs: "Damn, Musk! Looks like it'll be a quiet night for you at the secret lair. What a putz!"
Elon Musk: "Not so fast, cancer man. (take huge rip from blunt) There is still the sweaties inside that turned this foam party into the rinse cycle of a washing machine!"