Irish (possibly only Dublin, I'm not sure) slang meaning to kiss someone without warning.
Random onlooker: OMG! He just gobsmacked her! That looked painful.
by Francie July 24, 2005
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To be kissed without having a say in the matter.
Did you hear Peter gobsmacked me last night? The only was he was ever going to get his lips on me.
by nvidic June 25, 2009
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to unexpectedly or suddenly hit someone or something in the mouth. Often done in anger or with the intent to injure. Almost always done with whatever is nearest at hand.
"I gobsmacked that bully with my biology book."
"Billy said he was not going to get off my new bike. I gobsmacked him into changing his mind with my book bag."
by R Lord February 8, 2008
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Similar to a lemon party, this sexual act involved older and younger people, however it is an elderly lady with largely saggy boobs that is getting her 'gobs smacked' by a younger male.

Much like a kitten plays with a yarn of wool, batting it around in fascination, the young male smacks the old bat's boobs however he likes
It is also when an old lady wants to get a bit frisky and use her saggy boobs to smack a young male's gob or other parts of his body.
Male: Dude last night an old lady gobsmacked me, it was so good!

Old lady: Oh darling you wouldn't believe how well that 20 year old gobsmacked me last night, it was delightful!
by Bobetta Bobbington April 21, 2011
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