Someone who's a fan of anal penetration/sex; this person is usually male with a sweet, innocent, baby face until he gets you into the bedroom and turns you around for a bloody massacre or at least a seemingly innocent finger job on the rim. This person will also claim that anal is a commitment and a means to taking the relationship to "the next level." Note: Don't drop the soap.
(If the butt-sex killer is female, which rarely occurs, watch out for her from-the-back hugs and try not to leave the door unlocked while you shower.)
Also, the bsxklr (which is the abbreviation) should be noted as a well meaning type of person and should be appreciated and loved as such.

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