Songs that make you smile

[Mattress]

I searched for a thread like this but didn't find one, if this is a repeat, forgive me.

Anyway, what are the songs that when you hear them they just brighten up your day no matter how shitty a day it's been?

Also, give some reasons why you like the song so much.

Here's a few of mine:
Mogwai - Tracy (Playing with the Young Team Mix)
Just a beautiful base line from Mogwai and then Kid Loco adds in this fantastic melody that builds on itself quite beautifully.

dZihan & Kamien - Smile
Something fantastic happens in my brain when the girl singing in this song says, "Cuz I feel like, da da dada dada daiya" or something like that. it just a great fun song and I can't help but love it.