The 23-year-old actor, who played Jay Cartwright in the puerile E4 sitcom, was promoting the upcoming film spinoff alongside co-star Simon Bird on Alan Carr: Chatty Man.
Buckley jested: "I think we have rode our luck out. It's just a silly little programme, isn't it? It's a laugh. It's just s**t, isn't it?"
Last month, the Rock & Chips star lauded the comedy, describing it as something "Britain can be especially proud of".
Meanwhile, Bird - who plays Will McKenzie - explained that filming the movie was an "emotional" experience.
"The last week of filming was quite emotional because we spent so much time together over the last three years. Knowing it's coming to an end is horrible, really."
The Inbetweeners Movie, which also stars Joe Thomas (Simon Cooper) and Blake Harrison (Neil Sutherland) opens in cinemas on August 19.
> The Inbetweeners Movie is "final piece of the jigsaw"
> The Inbetweeners movie in pictures
Watch the Inbetweeners Movie trailer below: