The implication of either a) sarcasm (that is usually already overtly obvious) or b) a double entendre. Can be done just physically or both physically and verbally at the same time; but more often than not is just spoken.
Has been known to be shortened to "Nudge nudge" or nudging someone twice and saying, "Eh eh?"
a) "Scott is definitely not pussy whipped, wink wink nudge nudge"
b) "Let's have a round of golf, I'll let you play with my balls. Wink wink nudge nudge"