I'm Gonna Get You, Sucka
Dear Worried MotherSucker,
"Is it just a phase?" Well, before I give you the answer to that question, I want you to think about all of the adults in your life. Think about your friends, teachers, accountants, Costco checkers, wine store employees, firefighters, etc. All set? Now I want you to think about whether or not you've ever seen any of those people busily sucking away on their shirt collar while they go about their day. No, right? Because it is just a phase.
(But if your answer was "yes," you probably have more problems than can be answered via a free internet advice column, and I strongly advise you to move to a new town.)
I have to confess that both of my boys were shirt suckers back in their toddler days, and it drove me insane, too. First of all, it looks weird when they're doing it. Like they spilled some food there and they're getting another helping or something. Second, it makes the shirt looks all wet and gross and stretched out. And third, they're probably ingesting at least a little laundry detergent and that is the kind of knowledge that'll keep you up at night. ("Will he be the shortest kid in his graduating class because he sucked on all of that Woolite!?")
The reason kids do this sucking thing, in my experience so slow your roll, experts, is either for comfort or out of sheer habit. And to stop it with your son, maybe see if you can give him something else to hold onto or suck. I've seen parents use wrist sweatbands, which still looks weird, but at least takes the sucking out of reach a bit. You might also try giving him a little stress ball to squeeze. Anything that sort of distracts him and pulls his focus away from the shirt will work.
But take heart in knowing that it's just something he's going to grow out of doing before too long. At least that's what happened in my household.
Now the only shirt that gets that sucked on is my Justin Timberlake concert tee.