Geneva, I did this until about a year ago (I am 24). I did it a lot when I was living alone and without my family, I think it gave me comfort. It also helped me to fall asleep at night. I also have a small square of my baby blanket (from when I was a baby) that I still sleep with. I sort of sniff it lol while I'm going to sleep. I have a hard time sleeping without it. I wouldn't feel embarrassed, as far as I'm concerned it's better than biting your nails or smoking! Those are oral fixation activities too and I think they are worse than thumb sucking.