Front bum can refer to a pussy, or a big, nasty fat person's lap that looks like they have a butt upfront.

See: alcove, bat cave, bear trap, bearded clam, bearded taco, beaver, bermuda triangle, box, bucket seat, cake, chuff box, cockpit, cooch, coochie, coochie-pop, coose, cooter, cooze, crack, crawl space, cum depository, cum dumpster, cuntcake, cunt, cunny, donut, dripping delta, felted mound, fillet-o-fish, finger hut, fish, fish taco, fly catcher, fuckhole, garage, gash, gates of Heaven, golden doorway, Grand Canyon, growler, hair pie, hatchet wound, heaven's door, hole, honey cave, honey pot, hot box, jaws of Hell, lobster pot, loins, loose meat sandwich, lotus, love box, love canal, lower lips, meat wallet, muff, nooch, nook, nookie, peach, pearly panty gates, pocket, poon, poontang, purse, pussy, quiff, quim, rat trap, scratch, sheath, slash, slit, snapper, snatch, space, split, stench trench, tampon socket, temple, thingy, tool shed, tuna, tunnel, twat, undercut, vagina, vertical smile, wishing well, whisker box, womb, x, yoni