Great advice from the Jeremy Cook on the Tindie blog:

You Should Have Worn a 555 Timer T-Shirt

On your latest project you decided to use an Arduino breakout board, which seemed like a good choice at the time. A few lines of code, and your LEDs were happily blinking away. Of course your were thrilled to be featured on Hackaday, but after several choice comments, you realized that you really should have used a 555 timer.

To remind yourself and others that you should have really used a 555 timer, you really should have worn this NE555 Classic Timer shirt from HobbyElectro. It comes in black, with a diagram of this classic component emblazoned in white on the front.

One could wear it as a constant reminder to use this device instead of an Arduino, or as a sort of loyalty statement to this classic component. Alternatively, it could be given as a “gift” to others to point out their supposed mistake.