...and he was a little embarrassed. Paulie may have been trying to blend in; give the impression he was an invited guest. And then this "stupid jerk" is tossing sandwiches over the heads of the guests; drawing attention to Paulie the non-invited guest. In the movie or storyline context, FCC uses the wedding scene to establish many of the characters and their role in the family. It's a broad brush and a very effective one. In the first 15 minutes of the movie just think of all the characters you are introduced to.

My wife's Grandmother (God rest her soul) would spin many a story about the Italian coal miners in Northeast Pennsylvania. The wedding's were very humble affairs. Typical fare was a salami sandwich and a grape soda. Gobagool would have been a high class affair.