Last night I used the DMG random insanity table for the first time!
My kids took over control of some NPC to perform a heist while their main PCs were traveling elsewhere (off to a minor war-battle --- which we'd already played out many months ago but they still weren't back). The NPCs I gave them to choose from were all survivors, rescued from a magical prison which left most of them insane. My daughter wanted to play one of the insane ones, so we rolled twice on the DMG table and I let her pick the mental affliction.
First roll was manic-depressive, which was only so-so for the circumstances, but the second was schizoid. Per the DMG (pg 83):
Schizoid: This rather mild insanity form manifests its effects in a
personality loss. The afflicted has no personality of his or her own, so he
or she will select a role model and make every attempt possible to become
like that character. Selection will be based upon as different a person as is
possible with regard to the insane character. Thus an insane magic-user
will begin to follow the habits of a fighter, for example, dressing and
speaking like that character and seeking to be like him or her in all ways.
My daughter, who can sometimes be a very risk-adverse/passive player, leaned hard into this and it was hilarious*.
*Not saying Mental illness is funny...