ZIPLOC BAGS - male, because they hold everything in, but you can always see right through them.
SWISS ARMY KNIFE - male, because even though it appears useful for a wide variety of work, it spends most of its time just opening bottles.
KIDNEYS - female, because they always go to the bathroom in pairs.
SHOE - male, because it is usually unpolished, with its tongue hanging out.
COPIER - female, because once turned off, it takes a while to warm up. Because it is an effective reproductive device when the right buttons are pushed. Because it can wreak havoc when the wrong buttons are pushed.
TIRE - male, because it goes bald and often is over inflated.
HOT AIR BALLOON - male, because to get it to go anywhere you have to light a fire under it... and, of course, there's the hot air part.
SPONGES - female, because they are soft and squeezable and retain water.
WEB PAGE - female, because it is always getting hit on.
SUBWAY - male, because it uses the same old lines to pick people up.
HOURGLASS - female, because over time, the weight shifts to the bottom.
HAMMER - male, because it hasn't evolved much over the last 5,000 years, but it's handy to have around.
REMOTE CONTROL - female... Ha! You thought I'd say male. But consider it gives a man pleasure, he'd be lost without it, and while he doesn't always know the right buttons to push, he keeps trying