The modern day information age version of the old, "I'm off to buy a pack of cigarettes"
generally this means the person in question is never to be seen again.
Todd : Alright Andrew, after this game of pool, ill verse you.
Andrew : Yeah alright, i just have to duck out and buy some credit first.
*10 minutes later*
Brodie : Todd dude, were never seeing him again.
Todd: Ohhhhhhh, he was buying credit, damn.