There was an article here on the Net some time back, when employers are looking for new staff, they go straight to places like Facebook and the like and find out what sort of a person you are and what comments you have made.
Better not link your FB account to any stupid pranks on YouTube, wether you did them or not.
Regardless of the qualifications you hold, even if you played up a bit at University,youngun's be afraid, very afraid!