Ronald: Ah, the great outdoors. Bees buzzing... tummies rumbling...
This happens to Ronald himself on another commercial where he and a kid are on a dinosaur hunt.
In a 2005 commercial advertising the Chicken Selects, it shows a montage of a guy who's stomach growls very loudly in the most inconvenient situations. His narrative claims that since he tried the Selects for the first time, his stomach demanded them.
A restaurant called Bojangles has a series of commercials featuring this trope, in which important events are interrupted by a growling stomach and the character's pronouncement that 'It's Bo-time!'
An old commercial for Chef Boyardee ravioli has a boy's stomach growling louder and louder as he rides his bike home from school.
There's a 1997 commercial for Austin Crackers which features a boy who's stomach is growling like crazy. The growls are indicated by a lion inside of him.
In a late 90's Slim Jim commercial, a girl takes a bite out of a Slim Jim, but Slim Jim Man is not pleased with what else she has eaten and starts throwing stuff around. From the outside, the ruckus causes the girl's stomach to grumble.
This happens in a few Snickers commercials in the 80's.
There is a commercial for KFC where a dog gets confused by the growls from his owner's stomach and responds by growling and barking back at it.
There's several Lunchables commercials where a kid's stomach rumbles loudly and violently enough to have an earthquake-like effect on the kid's surroundings.
A recent car insurance commercial has a man buying and eating gas station sushi. He gets to work and starts using his computer, as his stomach lets out an unpleasant moan.
There's a commercial with Timer The Cheese Guy where he talks about this trope in a PSA that advises people not to skip breakfast in the mornings.