Commando

In internet slang, “commando” refers to a person who is not wearing any underwear. It is often used humorously or to add emphasis while discussing the absence of undergarments.

Examples:

1. I can’t believe he went to the party commando! It was so obvious when his pants slipped down.
2. She said she forgot to do laundry, so she had to go to work commando. She was really uncomfortable all day!