Leaves fold up after being touched through a process called thigmonasty

It's shy

Me too, plant. Me too.

Love these plants when I was little. Use to spend all of my time during recess just to look for these

It's a mimosa pudica :)
Also known as shy/sensitive plant or "touch me not"

Anybody else thinking of 'Mike tython' while reading the title?

There's plant that is either exactly this or related on the Hawaiian Islands. It's called sleeping grass, and it can actually cut your feet if you step on it again.

What is the evolutional point of this?

Where I'm from, we call these "moriviví" which basically translates to "I died but bitch I came back"