When someone has too much excitement about something.
Overenthusiasms can be annoying to others if they are too much.
Examples:
Her overenthusiasms about the party annoyed everyone.
His overenthusiasms for the new toy were too much.
Overenthusiasms can make people not want to be around you.
The dog's overenthusiasms for treats are always funny.
His overenthusiasms for video games are out of this world.
The overenthusiasms of the children at the amusement park were contagious.