We're/I'm (so) glad you could drop by spoken language
Said to someone who visits you unexpectedly or briefly
We're glad you could drop by. Next time bring your kids, too.
'We're glad you could drop by,' my father said to my uncle.
To visit
Go somewhere for a brief visit or purpose
A short visit
You are always welcome to visit
To stay away from someone's house permanently.
To be very wet
Because of forgetting bringing an umbrella, I look like a drowned rat when it rains.