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8.
This is when you kiss a women after licking her out, while she's on her period. The period blood should collect in your mouth and during the kiss you pass it onto her.

NOTE: If you wanna try this be aware that you can actually catch HIV from doing this as you're swaping blood.
"My boyfriend gave me a rainbow kiss"
by Blooddiamond21 August 31, 2007
76 73
 
9.
The act of a guy jizzing in a girls mouth and a girl getting period blood in a guys mouth, then kissing and sloshing it all together
Luke and I rainbow kissed last night... Never doing that again!
by Kingshockey66 April 07, 2014
5 3
 
10.
During a girls menstration the male performs oral sex and takes a mouthful of her blood. While the male has blood in his mouth the girl performs oral sex and takes a load. They then exchange a passionate kiss with their body secretions in their mouth through a kiss
When Sean was giving a rainbow kiss, to Vanessa he got a case of the red teeth.
by Killer Joe July 12, 2006
76 77
 
11.
When a girl is on her period and a guy licks her out.
Can also be when a guy licks out a girl when on her period and he kisses her after licking the pussy and transfers the period blood back into her mouth.
Only a real whore would attempt this.
1. I just gave this girl a rainbow kiss
2. You are fucking disgusting!

1. Never try a rainbow kiss, you will throw up
2. I know, me and this whore did it last night and we threw up in eachothers mouth !
by what was that! August 27, 2010
25 28
 
12.
when you go down on a girl during her period
girl a 's'pose nothing happened last night cos it's that time of month'

girl b ' actually he gave me a rainbow kiss'

girl a 'never had a guy game enough to do that to me b4'
by lantern January 22, 2007
14 17
 
13.
an extention of red socks
once red socks has been achieved the couple kiss and exchange the expelled blood
girl: shall we rainbow kiss now

Guy: (muffled) mmm hmm
by james J.D.R. April 08, 2011
4 10
 
14.
when a girls on her period and gets licked out then gives him head and they pull straight after.
im on my period finally so now we can have a rainbow kiss.
by doovde January 10, 2008
3 9