Who doesn't know Snape?
How dare you! You don't know my namesake's killer!
Oh wait, you know him? OK.
How would you like it if he voiced your GPS?!
SNAPE: "Turn right in 2 miles. Don't disappoint me."
SNAPE: "How grand it must be to have taken the luxury of not taking Exit 12. Turn around when possible, you bumbling idiot."
SNAPE: "How extraordinarily like your father you are; he would have missed the right turn-off too. Turn around and go back, you pathetic fool."
SNAPE: "There will be no foolish lane-merging or silly U-turns in the next mile." (as in first film: "There will be no foolish wand-waving or silly incantations in this class.")
SNAPE: "Turn to route 394." (as in HP3 -film: "Turn to page three hundred ninety four.")
SNAPE: "Alwayyyyys... look before merging."
Try saying them out loud like Snape. It took me 5 minutes to focus and say it without laughing for the "There will be no foolish lane-merging or silly U-turns in the next mile."
Source: http://failbook.failblog.org/2011/09/12/funny-facebook-fails-the-alan-rickman-gps/