My IP is -5919 wtf

That happened to me as well :/ but I logged out of the client and logged back in and it was fine

the real question is can you now buy everything since you are already negative.

I've never heard of that either actually, very odd.

Can you buy anything?

ya, that's very odd, hope riot support helps, send them a ticket

re logging fixes this bug it has happened to me as well.

We must summon Riot Ames to fix this atrocity

RAF abuse correction?

I'm guessing you had 6681 IP, bought a 6300 champion and it charged your IP twice on accident. Like everyone else said just log out and back in and it will probably correct itself.