look up any word, like plopping:
it started as people making fun of things some BMXers do, like nollie off of curbs, dip 3s, and nose bunk things, ect. it eventually just became a general response to any question asking why.
"why did john nollie off that curb?"

"because street"
"why did you not do the homework?"
by Franklyn newell October 02, 2013