Wiktionary
drop by
vb. to visit informally and spontaneously
WordNet
Usage examples of "drop by".
If he didnt drop by the house in the morning, he came by the marina in the afternoon.
She assured the folk that her road guards would drop by often to be sure that it was still in place and intact.
She stayed in her apartment, and occasionally some former customer would drop by--someone who had been very young to begin with, and was still acceptably young.
He took the shock of the drop by tucking a shoulder under and rolling, coming to his feet smoothly.
This she poured into the apprentice's open mouth, drop by subtle drop.
At first Johann held Maria in his arms and patiently let each kind of juice fall, drop by drop, upon her lips.