[HOO-sane],

1. n. The art of pretending you don't have a middle name.

They named their kid Judith Testicles Farnsworth. That kid better get good at whossein.

2.v.i. (informal) To question the use of one's middle name in response to a provocative calling-out. Used in this way, the word has connotations similar to "chill out."

"Richard Livingston Seagull Jr. come here right now and explain yourself!"

"Whoa, Mom. Whossein!"