Double meaning: A foul and compulsive liar of epic proportions. Also synonymous with shit. Named so after Ontario's Premier Dalton McGuinty who have broken every single one of his election promises for the last 8 years and yet has the nerves to continue to lie for a third term.
Excuse me sir but your dog just McGuinty'd on my lawn. Could you so kindly clean it up?
Dude, I took the biggest McGuinty this morning and was late for work.
Son, I was awake when you came home late last night so don't try to McGuinty me!