1) Mythical prototype board for working on bottoms of cars, includes such add-ons as tool set, can swivel, lock into place, etc...
2) Someone with little or no sexual dignity.
1) The mechanic saved up all his money for a year to buy a new ratchetboard, which greatly facilitated his work.
2) "Are you going out with Maggie dude?"
"No man, I hears she's a total ratchetboard"
"Yeah man, she gets around"