go dotty

1. To become somewhat eccentric, odd, or mentally unbalanced. Jackson started going dotty after spending a month by himself in his cabin. Sorry, what did you say? After months of sleep deprivation with a newborn, I think I've gone dotty. You can't tell people you want to start a business selling bees as pets—they'll think you've gone dotty!

2. To become forgetful or absent-minded, especially due to senility or old age in general. Grandpa's been going a bit dotty lately, I don't know if he can take care of himself anymore. Just because we are in our 70s doesn't mean we've gone dotty! You'd best treat your children well, for they're the ones who will care for you after you go dotty.

3. To become very excited or enthusiastic (about something). I've never understood that pop star's popularity, but kids just go dotty over her music. I bet everyone goes dotty over the new Roboformers movie—I've heard the special effects are really incredible. You know, I don't go dotty when I have to clean the kitchen after you cook—you always make such a mess!