A sancha is your second lady. Not your wife, or your girlfriend, but
your number two. If something were to happen to your wife or girlfriend (i.e.
freak accident) your sancha would be there to wipe away
your tears.
ex #1 "My wife is a prude in bed, but my
Sancha...
woo wee...she's a freak! Its like that whole
yin and yang thing!"
ex #2 Me: "I can do things with my
sancha that I just can't do with my wife."
Friend: "Like what eh?"
Me: "You know like sending her home, or anal or stuff like that"