Drop in and Stop by

[Namsteven]

Kevin: Hey John! What's up?

John: Nothing. I just want to stop by to say hi.
Nothin'. I just want to drop in to say hello to you.

- Do the sentences of John sound natural?

Thanks so much to friends!

NamSteven

[Conchita]

Your sentences sound natural, although they suggest that John hasn't stopped by (or dropped in) to see Kevin yet. A more common tense for the verb 'want' here is the past simple: 'I just wanted to...', especially if John is already at Kevin's house.