The term jack can mean various different things. Such as;
Jack...A persons name
Stealing..Man Ive been Jack-ed
Card game......Black Jack
Wining...Ive hit the Jack-pot
A man yelled jack, he saw that he was jack-in off. At this point a hooded figure Jack-ed the man jack-in off. He stole his Jack-et. Inside was lots of money, the theive decided to play black Jack, on the first deal he hit the Jack-pot.