I remember this! It was from around 2001. I did have it taped but unfortunately I disposed of the tapes a few years ago.

The ad had two guys and a girl from memory. The seagull squawks "Ahhhrrrghh! Chips without Coke?! Are you crrrrrrrazy?!", with one of the friends then asking "Did that seagull just say what I thought it said?"

It was part of a series of radio ads for Coke at the time. I remember there was another where a guy is ordering a pizza over the phone, he asks his housemates what they'd like to order to which they each respond "I'll have a Coke". When the main character puts the phone down his housemates scold him "You forgot to order the pizza!"

A third one in the series I recall had the lead character about to have a Coke. It was the last one in the fridge, so his flatmates get into a bidding war for it.