I caught pieces of this movie while my parents watched it in the living room years ago. A group of people were in a jungle somewhere and the nerdy male character (I think he had glasses but I’m under the impression he was the comic relief) suddenly shows up, slack jawed and unresponsive. The group starts to wonder what’s going on when the man slumps to the ground, revealing a huge gorilla behind him with his brain in its hand. I think the gorilla was unnaturally intelligent/hostile and started attacking the group but that’s where my memory ends. Thanks in advance!