Keira Knightley's latest advert for Coco Mademoiselle, which involves her covering her breasts with a hat.
Strangely enough, the bear in Orangina's first CGI commercial is wearing a leaf over his groin. It is strange because the other men are wearing trunks.
A large male cougar who appears in one of the print poster adverts has a normal-sized man sitting on his lap. The cougar is completely naked, and the (clothed) man's leg is the only thing lending the cat any modesty. The fact that the man's entire leg is attempting to cover the cougar's groin lends itself to comical implications.
Sophie Dahl did this for an advert, covering her breasts with her hands and crossing her legs to cover her groin.
A UK TV ad involving an old man covering his groin with a full shopping basket.
They did this in an ad campaign for Wireless computer products with monitors and towers covering the naughty bits.
A recurring theme in PETA advertisements, since they've mostly turned to pictures of pretty women, willing to pose naked and declare that they don't eat meat.
Or, as they often declare, "I'd rather go naked than wear fur".
An Italian(?) ad featured a variation: The model adapted a pose that actually gave a clear view of her pubic hair, with a caption to the effect of, "The only fur I am not ashamed to wear."
Parodied by The Onion. "I'd rather be raped by an animal than wear fur."
A FedEx advert has two naked models on a catwalk. The rear one is covering her bits with fanned out tickets, while the front one is using a flowerpot- the pot covering her groin and the two lots of attached flowers covering her breasts.
A Curry's ad did this, with customers and staff covering up with electrical appliances such as kettles and toasters. It also included a sly visual gag of having a concealing TV display a large cockerel on its screen.
Virgin Atlantic used this trope, in the form of a generic burlesque act, to promote discount fares with the slogan "We've Taken Loads Off".
Used in this IKEA advert, where a man and woman engage in some foreplay that results in the man losing his underwear and forced to use a framed photograph to cover his groin when they are walked in on by their children (mildly NSFW).
This Koolanoo commercial, where a woman loses her top in the pool and a man uses his hands to cover her breasts. (mildly NSFW)
Several adverts for impotence cures use the joke of a man not needing to hold the object over his genitals, implying it is hung there.
The infamous "Life is Short" ad for Xbox depicts a newborn baby being shot out of his mother before rapidly ageing while still airborne. As a baby and toddler his privates are covered by a trail of Censor Steam due to his speed, but when he grows into a pre-teen he begins covering himself up with both hands. It actually makes some degree of sense - outside the obvious - in that going that fast with no protection would be especially painful in that area and the boy is probably just acting instinctively.