How do i know....?

how can you tell if a girls last boyfriend had a bigger penis then you.... and what are the criteria for considering a girl to be loose....?

You can't really tell. Muscle goes back with time even if it has been stretched. There are no set criteria either, except this: if sex with her feels good, what do you care if she's considered loose or who she slept with. Also, keep in mind that if there isn't enough friction, that doesn't necessarily mean the girl is loose. Let's face it, maybe you're just small :P And while she can tighten up her vagina with exercises, there's nothing YOU can do to get bigger, so think first before accusing any girl of not being fit down there.

that was wrong pitaime lol but true lol