That’s great!
Most of my tees are from https://shirt.woot.com/ . A few of my favorites:
My favorite shirt store is shirt.woot. They have a huge selection of fun shirts.
A few of our favorites:
Pi=pie
Star Wars Cats
Dead Donut
Today (7/20) only they are offering $10 of purchase of $20 and free shipping (normally $5). I just bought three more shirts.
edit: ninja-ed by RTFirefly!
I’ve been seriously considering this Monty Python oneat RageOn for a while.
Zazzle has some fun tees. Here’s a few
How about this one?
I love it. But I’m Canadian.
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Some of those are great! Thanks.
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The XKCD store has some I like.
I have a tie-dyed Project Plowshare shirt up on my Zazzle store.
Quite the historical novelty…and you can have a fun time seeing the expressions on people’s faces if they read the line under the logo!
Sorry I don’t have a link to it atm but I custom made a T-shirt with “Don’t worry, it still works” across the chest.
For as long as I’ve had it, it’s still funny to watch random people’s faces as they see what it says. 
Lovecraft fans…don’t get TOO obscure.
I own an INNSMOUTH HIGH SCHOOL SWIM TEAM shirt that I never wear any more because everyone just assumes I was on a swim team in Innsmouth.
Even my MISKATONIC UNIVERSITY – METAPHYSICAL DEPARTMENT shirt gets ignored, except for the occasional inquiry about where Miskatonic Univeristy is, after which I have to explain that it doesn’t exist.
has always been my favorite
I think you should make your own, that says “Sent from my XT1635-02 using Tapatalk”.
My wife and I will be driving up to Idaho for the solar eclipse next month. I bought this t-shirt for us: https://www.amazon.com/gp/product/B071FGP16V/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1
Check out this ramen-eating t-shirt.
I kinda like this one
Why not tap some of the SDMB’s super T-shirt design talent? I’m sure more than one Doper would be willing to design a one-off for you. (And I live within walking distance of the place that prints my T-shirt designs, too!) 
Google T-shirts a few times then turn off your ad blocker. Google will inundate you with ideas and sites.