I voted "If I've had a couple" as I have in the past had 1 beer after work and then driven home, but I have also tested my BAC on a calibrated tester and I know I can have 2 beers in 2 hours and still be under .02, which is the limit for our site.
But luckily for me my wife doesn't drink at all so if we're going out I also have a designated driver