In the Busan stage spawn room of Overwatch, some characters have special karaoke voice lines that you can trigger by going to the karaoke room.
Despite just releasing on the PTR, Sigma already brings some new karaoke voice lines. He mutters and grunts in a strangely erotic tone and says "lekker stroopwafel," Dutch for "delicious syrup waffle." Stroopwafel is a popular pastry in the Netherlands, where Sigma hails from.
Some players and fans are disappointed that a new Hero gets karaoke lines before other fan favorites like D.Va and Lucio, while other fans are disturbed and delighted by this side of Sigma. Perhaps this is the melody that confounds him so?
These humorous aspects of the Heroes is what makes them so endearing, and giving a little more to newer Heroes to get them in the fan's attention can only help make Sigma feel like a welcome addition.
Sigma is live now on the PTR, so you can try him out for yourself now. Befitting the character, there are some eccentricities to his kit, detailed in another one of our articles about Sigma, so be sure to check out all this Hero has to offer.