You know the Beano? And the Bash Street Kids?
When they're about to tuck in to a mouth watering plate of bangers and mash (you know, the mountain of mash with sausages sticking out of the side), or an ice cream the size of a house, or a big chocolate bar...
You see them dribbling and there's a big caption in the cartoon frame going "SLLLUUUUUURRRRP"