They are male, because they hold everything in, but you can see right through them.
These are female, because once turned off; it takes a while to warm them up again. They are an effective reproductive device if the right buttons are pushed, but can also wreak havoc if you push the wrong buttons.
Tyres are male, because they go bald easily and are often over inflated
HOT AIR BALLOONS:
Also a male object, because to get them to go anywhere, you have to light a fire under their bum.
These are female, because they are soft, squeezable and retain water.
Female, because they're constantly being looked at and frequently getting hit on.
Definitely male, because they always use the same old lines for picking up people.
Egg timers are female because, over time, all the weight shifts to the bottom.
Male, because in the last 5000 years, they've hardly changed at all, and are occasionally handy to have around.
THE REMOTE CONTROL:
Female. Ha! You probably thought it would be male, but consider this: It easily gives a man pleasure, he'd be lost without it, and while he doesn't always know which buttons to push, he just keeps trying.
There are some other similar points in the answers, added by cordykitten