https://www.scientificamerican.com/article/after-being-swallowed-alive-water-beetle-stages-backdoor-escape-from-frogs-gut/

Being swallowed alive by a frog is a death sentence for most insects, but one beetle species shrugs off being digested and instead finds freedom by sneaking out through its captor's anus. 

When the pond frog Pelophylax nigromaculatus was presented with the aquatic beetle Regimbartia attenuata, it quickly snapped up the beetle, swallowing it whole and alive. But the meals ended with a strange twist, researchers recently discovered.