I'm generally curious if this has ever happened. If it has, or even if it hasn't, I'd like to see any such user rewarded with a badge.
[Badge name here] - Has hit the reputation cap for a day without posting a new question or answer
I don't know enough about the data schema and rules to quickly construct a query on data.stackexchange, but I thought about a query that was something like
-- They do it in their sleep -- Users that have achieved the reputation cap in a day without posting a question or answer