Ignore the erotic definitions made by horny teens below, but a blast from the past is something that was made from the past, but its very amazing, even to the present day.
Person 1: Whoa, Super Mario Bros for the NES is such a blast from the past!
Pesron 2: I know, right!
When you get older and look back at the young dumb days of your life. Drug use sex and country music.
Hey Randy you want to have a blast from the past?
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the act of thinking of (or popping up) previous sexual encounters while masturbating
i had a fuckin' great blast from the past last night man...cherie appeared in my head, you know the time in the pinewoods!
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a blast from the past is when you hook up with someone you previously dated or had history with and bust a nut on her.
"remember my ex from high school? i met her at that party and i gave her a blast from the past"
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The act of giving your grandfather a blowjob and having him ejaculate in your mouth.
"Hey dude, you want to hang out?"
"No thanks man, I'm going over my Grandpa's for a blast from the past."
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The act of ejaculating in ones anus then having that person fart a cum filled mess on to your face.
John: Oh cum in my asshole so i can give you a blast from the past.
Keith: Please punch me in the face after so i can make it a a neapolitan delight
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Giving your grandpa a blowjob and having him shoot his load in your mouth.
"Man grandpa, I sure love when you give me a blast from the past!"
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