An example of drop by is stopping at a friend's house while in their neighborhood to see if they are home.
She would drop by shortly to pick up her boarding pass for her flight to the golden west.
The temperature of his tent seemed to drop by ten degrees.
I'll tell Howard to get everything together and you can drop by to pick it up next week.
Rhyn, can you drop by the lake and bring a couple sets of clothes?
I drop by on occasion to check on my father's restaurants, he said with a quick glance around.