Literally: “To have hooked atoms”.
Meaning: To hit it off with somebody; to have a lot in common with somebody.
Origins: This expression possibly comes from the Greeks atomists such as Democritus and Epicure, between 420 and 270 BC. They had a theory that the bodies we see, owned their cohesion due to the crooked atoms, intertwined with each other to form a complex ramification. Later used in the 19th century, Goethe used this analogy to describe the attraction between two people. Proust also used it in his work: A la recherche du temps perdu ./ in Search of lost time.
Examples: “Il faut, ajoutait la femme du docteur, qui ne l’avait jamais vu faire autant de frais que vous en ayez ensemble des atomes crochus.” (M. Proust : A la recherche du temps perdu)