Cosmo, in an effort to compile a list of red flags for shady guys, asked its readers to finish the sentence "Never trust a guy who ... " Here are some of the best responses:

Never trust a guy who ...

  • Winks more than he smiles.
  • Can't go to the bathroom without taking his cell phone with him.
  • Says all of his exes are "crazy."
  • Gets frequent late night phone calls – and he isn't an on-call doctor.
  • Won't introduce you to his friends or family.