I used to Print T's for a living.. there was one manufacturer that sold a 20 X, and a 40 X shirt !
I think they were promotional things , for using them as a sign in the business window.. Still pretty huge !
the largest I ever saw in person was like a 10x .....
I will never forget the time we printed a teams sports shirts the night before a game.. this one shirt was a Youth Large, but it had Adult Large long sleeves sewn on it,,, we packed it up and sent it out as we had no substitute. But unless that kid was built like an Orangutan, it had to have fit funny ! hahahahahah We always joked that when the Mom called into complain we will tell her..
"There isn't anything wrong with that shirt, your kid is a mutant !"
memories.......