For example, he/she has recently learned colons in English class, and he/she proceeds to use colons in every paragraph of an essay.
"marked by excessive enthusiasm for and intense devotion to a cause or idea" "fanatical, rabid, passionate" "If you're overzealous about something, you've gone too far, and you're probably starting to scare people. Parents who are overzealous about keeping their kids safe may not allow them out of the house — ever. If you are overzealous about conserving water, you might shower a little too infrequently, or scold people for washing their cars. Most people understand that you mean well, and that's why you are so intense."