exhaustion erection
Slang term for an erection that occurs when one is physically exhausted, often used in casual or vulgar contexts.
After pulling an all-nighter, I got an exhaustion erection.
Rarely used kanji form; the second kanji is uncommon.
Compound of 疲れ (tsukare, 'fatigue') and マラ (mara, slang for 'penis'). The exact origin is uncertain, but it likely arose in informal speech.