It has often been suggested that English should have male and female nouns. Here are a few candidates for consideration as useful male and female nouns:

• 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.
• Penlight
  male, because it can be turned on very easily, but isn't very bright.
• 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.
• 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. Also, because it is an effective reproductive device when the right buttons are pushed. Also, because it can wreak havoc when the wrong buttons are pushed.
• Ziploc Bags
  male, because they hold everything in, but you can always see right through them.
• 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 and it's good for killing bugs.