Left-field t-shirt company ClothMoth have a fantastic t-shirt celebrating the joys of serotonin.
The shirt will cost you $18 and will allow you to advertise your love for one of the key monoamine neurotransmitters in the brain.
Tryptophan is an essential amino acid that is synthesised into serotonin. It is found in many fruits, nuts and vegetables. Walnuts are a particularly good source.
It’s not clear how many walnuts were eaten to produce this t-shirt, but the results are fantastic anyway.
Mind Hacks 
Just a quick note to let you know that we’re reprinting a limited run of YAY Serotonin! t-shirts after a two year hiatus. There’s 1 week and 4 days left to snag one in our presale-only event . . . 41 more orders and the deal is on! Feel free to share with your friends / readers and hope you are well! Order at http://www.teespring.com/yayserotonin. – Joshua / ClothMoth