There's a lot of new stuff going on in Fortnite Chapter 2 with its big new map at the centerpiece. This time around, Epic is making discovery part of the fun by graying out the map until you see an area for the first time. But players have discovered a likely unintended bug that grants players 2,000 XP each match just for crossing a few bridges.
The exploit revolves around the four bridges seen below. Per the map's grid, they're located at E2, C3, G4, and F7. Crossing any of the bridges (or just entering their vicinity) will reward you 2,000 XP for a total of 8,000 XP if you visit all four. You can repeat this process with every match to get a nice little XP farm going.
Assuming this is a bug, don't expect it to last long. But while it's around, use it as a nice pit stop for easy XP while you're playing the game normally. Or, go hard and try to hit all four bridges like your life depends on it. Though be ready for the possibility that widespread knowledge of the bug might turn each bridge into a king-of-the-hill warzone.
Update 10/18/19: As pointed out to me in the comments, exploiting a bug in Fortnite does break Epic's community rules, as outlined here. This is different from the Terms of Service that players agree to, but Epic states it can take action against rule-breakers nonetheless. So if you use this XP exploit, consider yourself warned! Though, I don't anticipate Epic bringing down a ban hammer for a harmless bug anytime soon.