look up any word, like plopping:
 
1.
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?"
"BECAUSE STREET"
by Franklyn newell October 02, 2013