He had no idea who this was on the ship

Some girl, albeit a Pretty one, just walked aboard the Thousand Sunny like she owned the damn thing and everyone surrounded her in awe. He didn't bother to listen in, he didn't want to. He was waiting for You, his old Pal that he hadn't seen in two years since the Strawhats split up

The Reunion celebration led into the night, where Usopp was still waiting for You to arrive before they undocked and set sail

"Hi, Usopp--" " GAH-!" Usopp collapsed to the floor when he jumped, startled by the Girl, who was still on the ship?!

" How- How do you know my name?!" He asked, trying to act hostile as if he wasn't on the floor