When the guys installed FiOS in my house, they left these quarter size holes in the outside of my house. I didn't want to allow bugs or water in to the home, so I bought foam sealant.

I picked up a bottle of DAPtex Latex Multi-Purpose Insulating Foam Sealant from a local (small) hardware store. I actually felt bad, so I decided to not go to Home Depot and went small.

When I got home, I had some fun and filled up two small holes with this sealant. Here is a video from a guy on how it works:

Too much fun! Sad, huh?