Baby Glenn is a man who made news during the 1980s when he fell in a hole.
According to Will, Baby Glenn was not "actually a baby" when he was a baby as he was already 13 years old at the time; the media only gave him the name because he did not stop crying for three days straight. After the coverage of his rescue, Baby Glenn evidently enjoyed the media attention and took advantage of his popularity, retaining the nickname given to him. He considers Jessica "Baby Jessica" McClure, who fell in a well at 18 months in 1987, his rival.
Baby Glenn later meets another minor celebrity Jack McFarland and the two immediately decide to date to "multiply" their fame, although they do not seem to be interested in each other romantically. Jack's friend Will includes Baby Glenn in the charity auction he is organizing, where Baby Glenn is able to raise $1100 to Will's surprise.