Some linguists (Jackson H and Stockwell P) single out relevance as of greater importance than Grice recognised. Assuming that the cooperative principle is at work in most conversations, we can see how hearers will try to find meaning in utterances that seem meaningless or irrelevant. We assume that there must be a reason for these. Jackson and Stockwell cite a conversation between a shopkeeper and a 16-year old customer:
Customer: Just these, please.
Shopkeeper: Are you eighteen?
Customer: Oh, I'm from Middlesbrough.
Shopkeeper: (after a brief pause) OK (serves beer to him).