I'm not sure how great pigs are at learning voice commands like that. We had one who would popcorn if we said, "Popcorn!" a few times in a really excited voice, but I'm not sure if she understood what we wanted or if we were just winding her up with our enthusiasm! Also, she was the smartest pig we ever had, the others didn't seem to have her aptitude for tricks.
Our will run over to the bars if they think we might have food (and they know who is most likely to feed them and are most enthusiastic about him!) and they do seem to get excited if I say they are getting treats (they do seem to know the word), but again, it's all food motivated! LOL!