Freefall: In this strip,Florence Ambrose's stomach growling is misinterpreted by a bystander as a regular wolf growl, and accordingly makes himself scarce in spite of Florence's yelled (and ultimately futile) reassurance that it was just her stomach growling.
In one El Goonish Shivestrip, Elliot and Ashley are on a date at the mall, and are discussing whether to go directly to the food court, or to wander around a bit first. Both mistakenly assume that the other is not hungry, and suggest looking around a bit, before being interrupted by simultaneous stomach growling. Needless to say, they immediately go get food.
Chapter 39 of Yumi's Cells shows how hunger works in a world where cells are microscopic humans: when Yumi's hungry, her Hunger Cell freaks out and starts playing a "Belly Flute" that translates into stomach noises. And in the issue in question, Yumi's stomach lets out a loud growl in the middle of a date as a result of skipping breakfast and only eating a light lunch that day.
Grrl Power: After consuming an extremely spicy alien dish called grakz, Sydney learns from Cora that it's 10 times hotter on the way out. Just after Cora leaves, Sydney's look of wide-eyed horror is accompanied by a sinister gurgling noise, leading her to start shaking and whimper "I'm scared." As the next strip shows, her fear was justified.
Questionable Content: Faye gives Angus a mocha, not knowing that he's lactose intolerant. Disturbing gut noises immediately ensue, which leads to him turning the bathroom into a toxic waste dump.