(It’s all about some English expressions using the bodypart-term ass, but without any reference to human buttocks. The verb fuck (up), figuratively ‘mishandle, damage, ruin’, puts in a cameo appearance at the beginning. But: no actual bodyparts, no sexual acts, presented either verbally or visually.)
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The verb half-ass, here ‘do (something) incompletely or incompetently’ — as opposed to totally messing it up
We start with the racy slang verb half-ass and work back from there.