I believe they used to sell one variation of that shirt in the park stores. Not sure if they still do, you may want to check the Disney Parks Shopping App to see if it is listed. If not, I imagine that some 3rd party unofficial versions could be found on RedBubble, TeePublic or a similar site.
I didn't see any in Magic Kingdom nor Epcot (and I looked). I also looked in Disney Springs today...nothing! I was hoping one of the resorts might have it.
The last ones we bought for our (adult) sons were bought at World of Disney, but I seem to recall seeing them in the Mouse Gears store too. However, that was in 2014. Would hate to see something like that disappear!!
Someone already said Tee Public and Red Bubble. Also, there's a woman on Etsy, The Craftiest Place on Earth, who sells it in a decal. She might have had a shirt too.
They don't sell them anymore unfortunately. They did have a new variation last year that said "please stand clear of my vacation." In Spanish of course. But they stopped selling the doors one.
They don't sell them anymore unfortunately. They did have a new variation last year that said "please stand clear of my vacation." In Spanish of course. But they stopped selling the doors one.