When acting out dialog an animator (or actor) may tend accent every syllable or action with a pose or hand gesture. This is an easy trap to fall into because once we force ourselves to think and analyze conversations, especially when breaking it down to 24 fps, we no longer act "naturally" and tend to add movements and gestures no person would actually do in real conversation. You end up creating a scene with so many accents that nothing stands out and one which confuses the viewers, or worse, takes them out of the movie completely. Watch the clip below of Nic Cage over emphasizing:
"Not one time!"
Remember kids, overacting is bad! (Although it can be quite funny once taken out of the movie and shown to the world)