I laughed out loud, but you don’t have to if you don’t want to.
Maybe if it wasn’t a sans serif font….
I think the joke is that Helvetica is a serious typeface designed and used by professionals who know typography. The font actually used on the shirt, however, is Comic Sans—and is hated by all typographers. There are even calls on the Internet to ban Comic Sans, because people who don’t know anything about typography are uglifying the world by using it for signs and company logos.
See this: http://comicsanscriminal.com/
That’s kind of embarrassing.
Seriously though, I did wonder when I looked at it, and noticed that it didn’t look anything like Helvetica. I just assumed there were variants.