The can of shrimp played the role of Alcee and Calixta encounter because that was one of the reasons Bobinot and Bibi went to the store. If Bobinot and Bibi did not go to the store then Alcee may have not gone to Calixta house. I mean you could say “How would he have known?”. Although the story does not tell you, how else did Bobinot and Bibi get to the store? Nonetheless, maybe if Bobinot did not spend time thinking about the can of shrimp he might have gotten home before the rain, but Bobinot did not. As a result, Alcee went to Calixta’s house during the rain, and Bobinot was not at home. He flirted multiple times, and Alcee and Calixta ended up in bed together. Then again, the can of shrimp also could have made Calixta realize where her heart really belonged too.