2. To be hit forceably in the mouth.
Seeing that water skiing squirrel has left me gob smacked!
2. I got my gob smacked last night when I gave my woman a dirty sanchez.
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.
Old lady: Oh darling you wouldn't believe how well that 20 year old gobsmacked me last night, it was delightful!