Without Valentine's Day, February would be... well, January.

Gaffigan’s joke hinges on the shared cultural sense that January is a bleak, post-holiday slog—cold, dark, and seemingly endless. By saying February would be “well, January” without Valentine’s Day, he suggests that the month’s main distinguishing feature (beyond being shorter) is a single commercial-romantic holiday that breaks up winter monotony. The humor comes from deflating Valentine’s Day’s supposed grandeur: it’s not portrayed as profound, but as a small psychological marker that makes February feel like it has an identity. The line also lightly satirizes how holidays function as emotional signposts in modern life.