The passage contrasts two types of relationships often found in transactional situations, namely those with a "John" and a "sucker." A "sucker" is someone who requires constant vigilance and gives nothing in return, with the interaction being purely exploitative. In such cases, the other party feels the need to be on guard at all times.

In contrast, a "John" represents a more mutual exchange where there is an understanding that both parties benefit from the interaction. The quote suggests that in this dynamic, both individuals can enjoy themselves, as the one providing the service recognizes the arrangement and actively participates in making it pleasurable for both. The overall tone implies that while both relationships may be transactional, the experience with a "John" is markedly more positive and engaging.