Pants

Pants isn't a word that needs to be plural.  If I wear a pants to work. . . maybe "if" wasn't the right word there. . . when I put on pants in the morning, it is just one unit.  When I asked this question to a friend, he suggested it is because I have two legs.  One pant for each leg.

 I feel like if they are going to sell them to me in the plural, then I should have the option of buying only one.  Sell me one pant leg for the times that I tear a hole in only one knee.

The reply to my friend was simple,  "I have two arms and I wear a shirt, not a shirts.  My wife has two breasts and wears a bra, not a bras."

That was the end of the conversation.  I think talking about my wife's breasts made him uncomfortable.