Most iPhone owners say they couldn’t do without the gadget, and quite a few would sooner give up sex, according to a new survey.

Ahead of the iPhone’s fifth birthday, on June 29, Electronics trade-in site Gazelle polled more than 1,000 customers who have traded in at least one iPhone.

It found that 65 percent said the iPhone was the device or platform they would not be able to live without, compared with just 1 percent opting for Facebook.

But the juicy stat is that nearly 15 percent of respondents said they’d rather give up sex than go for even a weekend without their iPhone. And nearly 4 percent of reported having used their iPhone during sex. Keep that up and you won’t have to choose between sex and the iPhone for long.

More than 25 percent said they ‘”almost always” use their iPhone in a social setting such a meal or party, while 58 percent said they do so “usually” or “occasionally.” Nearly 85 percent said they used their iPhone in the bathroom.

The iPhone has led nearly 70 percent of respondents to ditch their iPod or mp3 player, 55 percent to get rid of their camera and more than 40 percent to toss their GPS unit.

Finally, Gazelle reported that nearly 40 percent said a bigger screen is the feature they most want on the next iPhone. No word on how many want Siri to become more “full service.”