During Hagrid's second year at Hogwarts, he had once gone for a swim in the Great Lake and had an encounter with the local squid. The squid has grabbed Hagrid's leg and attempted to pull him under the water. Hag rid instinctively grabbed his wand and tried to shrink the squid, but it didn't work.
What happened? Let's just say the squid got in the way of a bad Engorgement spell.