My boys were getting ready to go to Scout Camp. They wanted a t-shirt they could wear instead of their uniform shirt all the time. They had a fun time trying to decide on something clever. Here is the end result. If you say it quickly . . .
We used heat press vinyl. I just use my DRY iron on the highest setting since I don't have a heat press. It works pretty well. Simply use a sheet of parchment paper over the vinyl so it doesn't stick to your iron. If you do two sided shirts, be sure to use a piece of parchment on the reverse side as well!
I do have a son that doesn't particular like his picture to be taken - thus the headless t-shirt.