Bus Pants 

They are pants one wears over one's regular pants when one sits on bus seats that other people have previously sat on.

This term was first seen on an episode of The Big Bang Theory titled "The Bus Pants Utilization".

Sheldon: All right, I suppose I'll go put on my bus pants.
Leonard: What the hell are bus pants?
Sheldon: They are pants one wears over one's regular pants when one sits on bus seats that other people have previously sat on.

Bus Pants by Mr. Oxford Comma January 7, 2011

bus pants 

The pants one wears over one's regular pants when one sits on bus seats that another people have previously sat on.

British English uses the term "bus trousers".

Example A:
- "All right, I suppose I'll go put on my bus pants."
- "What the heck are bus pants?"
- "They are pants one wears over one's regular pants when one sits on bus seats that another people have previously sat on."

-- The Big Bang Theory Season 4 Episode 12 (6 January 2011).

Example B:
- "Hey, I am not able to drive you to work today."
- "Don't worry, I'll just put on my bus pants and use a bus."

Example C:
In a bus, referring to a man with two pants on.
- "Look at that man. What is he wearing?"
- "Bus pants, obviously."

bus pants by Life_peer January 10, 2011

Bus Pants 

Bus pants are pants that have been worn on a bus or at school. Bus pants are not allowed in many places

"Hey, Sara? Can I sit on your bed?"
"Are you wearing bus pants?"
"Yes."
"Then, no."

Bus Pants by SKonicoff_Luver September 20, 2011