What's wrong with joining corona parties? In this article, I defend the idea that reasons to avoid such parties (or collective harms, more generally) come in degrees. I approach this issue from a participation-based perspective. Specifically, I argue that the more people are already joining the party, and the more likely it is that the virus will spread among everyone, the stronger the participation-based reason not to join. In defense of these degrees, I argue that they covary with the expression of certain attitudes.