According to Spreadshirt, a cool design for matching best friend t-shirts is text that reads, "She's my best friend," above a cartoon-like hand that points in the direction of the other person. This evokes novelty t-shirts emblazoned with similar graphics and the phrase, "I'm with stupid."
Shirts with an image of a hand with crossed fingers accompanied by the text, "We're like this," could also make cool best friend t-shirts, according to Spreadshirt. There are shirts featuring corresponding halves to a heart, a nod to charm bracelets and necklaces that some best friends wear. When two people wearing these shirts stand beside one another, the two halves come together to read, "Best friends forever." Another cool idea is shirts that simply state, "My best friend has the same shirt."