There was a woman at my LYS knit night last night who was knitting socks for one of the other women. She even showed her the pattern she was using!
Unless there are circumstances we don't know about I agree with the others about knitting in front of them all. Someone might ask who you are knitting it for, but just say "a friend" and leave it at that. After all, your uncle is a friend or you wouldn't be going to all the trouble of knitting a giant afghan for him, no?