What makes the phrase sometimes funny/abrasive is the implied 100% ownership of "it" (i.e., come to papa).
Often implies a diminutive order (Send it, sucka!) to immediately send/give whatever "it" is to the speaker (Dat's ALL mine; hand it over!) and it is usually said in a self-congratulatory tone (I am awesome, it is awesome, thus it is mine; ship it).
Poker usage: "Ship it" conveys a confident and impatient 100% ownership of the money in the pot. Saying "ship it" with a mediocre-but-still-winning poker hand usually gets a laugh, especially if you say "Ship it" after showing your weak hand but before you see the other person's weaker hand. It also usually gets a laugh if you say "Ship it" when the pot is tiny and uncontested... ship it, ship it all.
You look nice in them jeans. Ship it.
You've got the answer-key???? Ship it.
Everyone folds to me in the big blind??? Ship it.
Said at Foxwoods, before taking down a $1400 pot against an expected low (busted) flush draw: "Queen high. Ship it!"
2)OR a reinforcement of the awesomeness that has occured in the past.
3)OR the act of giving someone something awesome.
Dude2: Ship it.
Dude1: Did you score with that hot chick last night?
Dude2: Consider it shipped.
Dude1: You were wasted last night.
Dude2: Yeah, that cocktail waitress shipped me seven jaeger bombs.
Programmer - "Ship It!"