Was this incredibly rude of my co-worker?

Our manager takes us out to dinner whenever we have a good month of sales. It's always at a good restaurant. Anyway, my co-worker, Oso, said he wasn't hungry and that he would just drink. Towards the end of the dinner I overheard him whisper to the waiter, "Hey buddy, could I place a take-out order of prime-rib and put it on the same bill, and I'll take it with me?"