Dunno, it's a comfy tagline. I never got into Ruby but it always feels to me like it's a really ergonomic and cozy language. Sure, the best friend thing is a stretch, but it's honestly a slogan. How many people land on this page with no knowledge of what Ruby is and will confuse it with an app to make friends?
It sure is a comfy tagline, but because it doesn't really mean anything you could say it about any language, and it only works if you already know what Ruby is. It's not that anyone would confused Ruby with an app to make friends, but it doesn't really say anything about Ruby at all. As other pointed out, the page doesn't even make clear that Ruby is a programming language.