Well... assuming his butt and genitals are similarly covered.... what actually does the vacuum of space do to exposed skin?
"(...)After about 10 seconds or so, your skin and the tissue underneath will begin to swell as the water in your body starts to vaporise in the absence of atmospheric pressure. You won't balloon to the point of exploding, though, since human skin is strong enough to keep from bursting; and, if you're brought back to atmospheric pressure, your skin and tissue will return to normal.
It also won't affect your blood, since your circulatory system is able to keep your blood pressure regulated, unless you go into shock. The moisture on your tongue may begin to boil, though, as reported by Jim LeBlanc, who was exposed to near vacuum in a test chamber in 1965. LeBlanc's suit sprung a leak, and he remained conscious for about 14 seconds; his last sensation was bubbling on his tongue (he was safely revived, as the researchers began repressurising the chamber almost immediately -- after about 15 seconds).
Because you will be exposed to unfiltered cosmic radiation, you can expect some nasty sunburn, and you'll probably also get a case of decompression sickness.You would not, however, freeze straight away, despite the extremely cold temperatures; heat does not leave the body quickly enough for you to freeze before you suffocate, due to the lack of both convection and conduction. (...)"
Gamora should be okay since she has been enhanced; she'd suffocate, but she wouldn't poop her pants or burst her eye capillaries, probably. But Quill? Hmmm.