"We had a fair idea that this one was going to get a good reception, but I think it's fair to say that the scale of the phenomenon that it's become has been a bit of a ... pleasant surprise," Mr Knackstedt said.
"It's been picked up and it's got a life of its own and it's fantastic, because really you're looking at the young 15- to 24-year-olds who are in that space and that's who we're trying to reach with this message."
Mr Knackstedt said the appeal came down to the ad's authenticity.
"It rings true, the dialogue, and the humour obviously."
Mr Knackstedt said the ad reinforced the positives, but also touched on the consequences of drink driving.
"It's really important to remember that it's about the message, and the message is to get young men to stop their mates from driving drunk," he said.
"It is important from time to time that you remind people what the consequences are, but it's also important that you show people there's an alternative, that there's a positive choice they can make."
The ad was part of NZTA's Legend campaign, which would also feature billboards, radio ads and advertising at pubs.
NZTA chief executive Geoff Dangerfield said although the positive response to the campaign was encouraging, the ultimate success would be to see young New Zealanders take up the challenge of speaking up and stopping their mates from driving drunk.
"We've had a wave of great feedback from across the country, but we are under no illusions about the scale and the seriousness of the drink driving problem in New Zealand, particularly among young people," he said.
"We all have a responsibility to help stop drink driving, but we need young people and young men in particular to know that they can speak up to stop their mates from driving drunk."
About 200 young drink drivers were involved in fatal or serious injury crashes each year, with more than 40 per cent all drink driving crashes involving drivers under the age of 24.
