In American English, we often use the following phrases:
My friend popped in unexpectedly.
My friend dropped by for coffee.
We do not say "dropped round" or "dropped around" , but you can some my friend "came around" the other day...
And just for fun.... ;-) To "pop" someone in a rap song is to shoot them; to "pop" someone in the south meant to hit them; when you drink a pop you are drinking a soda; pop music is the newest music; when you "pop" the question you are asking someone to marry you; when you take a pill you pop a pill....should I stop???