Congrats to all of you who quickly and correctly guessed that Peanut has become a Tiger Cub. (Accepted answers also included "cub scout" -- the more general term -- and "boy scout.") And because I am feeling generous, I am going to give all of you shout outs! Thanks to Kristin, Kelly, Kristen, Heather, and Laura (who even specifically guessed "Tiger Cub"!) for participating.
Both my husband and my brother were cub scouts, so when Peanut heard that and some of daddy's stories of the pinewood derby, he was interested. Before that, he was really concerned that being a cub scout would entail us dropping him off in the far-off woods with only a tent to protect him from the bears. We assured him that we wouldn't do that until he was much older. ;)