look up any word, like the eiffel tower:
 
1.
A feminine, homo-type of a male. Used several times in the movie "Tombstone"
Curly Bill, Ringo and their Cowboy
entourage form a block in the center
Rows while BILLY BREKENRIDGE, Behan's bespectacled, slightly
effeminate little Deputy makes his timid way down the aisle,
looking for a seat midst the off fist-fight and yelling match.
2 cocky young Cowboys, BILLY GROUNDS and ZWING HUNT, call out
to him:

HUNT: "Hey, Sister Boy!"
by Matthew Boyd August 07, 2005
 
2.
A boy thatyou know and have the same kind of relationship as a sister or girl with.
I took my sisterboy shopping and we picked out cute matching outfitts ;)
by Sweetyboy, huggs n Kisses July 23, 2010