Is it a sign when your crush purposely bumps into you?

Well, honey, unless your crush is blind as a bat or has the coordination of a drunk flamingo, then yes, it's safe to say that bumping into you on purpose is definitely a sign. They're either trying to get your attention or they need to work on their spatial awareness. Either way, take it as a flirty nudge or a clumsy collision, it's up to you to decide if you want to make a move or Dodge their advances.