She left her husband and ran off with some young 'stud'.
retired racehorses being used as 'studs'
a horse that has been 'put out to stud'
(..) Oh, yeah. Oh, God damn. You are the best-looking girl I've had today. Oh. Yo, stud! Time's up, buddy. Coming in, ready or not. Hey, buddy, did you have yourself a good time? Whoa. (..)2003 Kill Bill: Vol. 1