"Hecking" is a piece of internet slang, from the past few years, which is used as a much, much more moderate form of the adjective fucking. Using such a mild "curse" word is an intentionally cute form of self-censorship used to draw attention to the cute and playful nature of the thing being discussed, or the person doing the discussing. Sometimes, for added effect, the word is even censored down to "h*cking". Use of the term might also have to do with YouTube or Twitch streamers needing to maintain good language for marketing purposes.
People from 5 years from now, I promise this all makes sense.