The act of your partner vomiting up Lucky Charm's cereal on your schlong upon oral sex, typically resulting in a rainbow-like hue.
"Ay lads, looks like I got ye olde Rainbow Pecker last night with Becky..."
"Sorry boys, can't make the movie tonight. Got another case of the Rainbow Pecker."
"Sorry boys, can't make the movie tonight. Got another case of the Rainbow Pecker."
by Brother Wumbo December 16, 2019