I found it!

Silas' first Halloween! He was only 3 1/2 months old. It's kind of hard to see the costume, but he was a lamb! Complete with felt head and ears, thermal body, and white fleece pants covered in cotton balls.

Looking at this picture is just weird. The boy has cheeks for weeks. He was such a skinny baby I hardly remember these cheeks, but at one time, he did have them. Now I've got a young enough picture posted for hard, cold proof!