You can imagine a t-shirt with the sleeves removed at the shoulder seam. Not quite a singlet.
I could imagine that yesterday but I was wondering how silly (or indeed cool) you actually looked in one...
Luckily for you and the internet, the temperature has dropped enough today that there won't be a chance to reenact it for a photo. But on days like that I think it is the overdressed people who look more silly.
Maybe you can sell tickets to the gun show.