To do something for someone, when it seems stupid, explain something, physically do something for specified person...etc..etc
"You're too funny.."
"Gee, I dunno..."
Going along with something that seems stupid or pointless for the sake of the other person.
Perhaps agreeing with someone just to keep them happy.
Person 1: Dude, come check out my totally awesome ninja pencil!
Person 2: Yeah..... no thanks...
Person 1: Naw, come on...humor me!
to make someone less angry or to make someone happy or to fix something
Her: You were supposed to meet me at 8. Humor me.
Him: Sorry hun. Couldnt be avoided. Let me make it up to you now.