Engaging in intercourse with a female who is pregnant with a child that is (at least presumably) not yours. This term only applies to heterosexual males. See 'Tonya Tub Thumper' for lesbians with strap-ons.

CAUTION: THIS ACT IS NOT ENCOURAGED AS IT MAY LEAD TO FETUSES GETTING POKED IN THE EYES
That dude is porking her in the third trimester, he's such a Turner Tub Thumper.

If there's a bun in the oven, don't worry about stoppin the lovin' -Turner Tub Thumper
by Buck Whittaker June 30, 2009
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