Have you ever caught yourself looking somewhere you didn’t want to look at?
Leaning down, sitting, holding on to the handrails in public transport people often unintentionally demonstrate their underwear and people around them unintentionally see it and feel uncomfortable. I thought it would be great if the random demonstration of underwear could carry a certain message, show the personality of the owner and mitigate the awkwardness of the situation when someone looked at something he didn't want to see. 
So there were Buttwaister underwear.