Lindsay Lohan and/or being very colorful, radiating a similar positive vibe, generating smiles.
Originally she was refered to as Lindsay "Rainbow" Lohan because her fans imagined that's what she would smell like (like a rainbow). But since 'rainbow' can also be used to describe her appearance - in it being very colorful and radiating a similar positive vibe, generating smiles and so on, she quite simply became Mrs. Rainbow - a person able to bring colors into our lives and positive vibes into our hearts.
by Rooster Fitdse October 24, 2006
Get the Mrs. Rainbow mug.
an amazing duck that roars like a lion.

brings happiness to everyone that comes accross is.
if only i could have mr. rainbow snugglebottoms, i would be happy forever.
by you.know. March 11, 2009
Get the mr. rainbow snugglebottoms mug.
Someone who is so very gay that it's undeniable at this point.
Person A: OKAY BUT CAN WE TALK ABOUT HOW DANNY WENT TO ANDREW, MR. TRIPLE RAINBOW GAY, TO TALK ABOUT GIRLS????

Person B: That's, like, the best description of Andrew-
by ThatShittyHomestuckWeeb October 27, 2018
Get the Mr. Triple Rainbow Gay mug.