Rios and Rios: Not Again! (2010)

Melanie and Valerie Rios, a pair of sexy but inept sister sleuths, are hired to protect a old woman from harm. The female private detectives discover that the dithering dame they are protecting is an impostor, but before they can act on the information they are captured, stripped, gagged and securely bound. One of the damsels manages to escape, but the crooks force the Melanie to stand in the hot sun, bound and naked, as bait to lure the escapee back into the clutches. The plan works and soon Valerie is returned to naked captivity. As punishment the two naked young women are tied to stools with their legs splayed, the better to insert hyperactive vibrators between their thighs. Struggling mightily, the detectives desperately try to remove the diabolical machines before they are forced to surrender to the pulsing within their nether regions.