look up any word, like eiffel tower:
 
1.
A half sibling via your father

ie from his 'spunk donation'

usually applying to promiscuous men with more than one family.
I didn't know you had a brother/sister - Oh he's my "Spunk Brother / Sister"

Underlining the fact that the relationship is not a close one.
by Big Superfuzz April 02, 2009

Words related to Spunk Brother / Sister

half brother half sister sperm sibling step brother step sister