EVERYONE DROP WHAT YOU'RE DOING
https://www.reddit.com/r/Games/comments/3y7maa/something_is_really_wrong_with_steam_be_careful/
There's some insane vulnerability with Steam going on, where many people are 'logged in' as other accounts. Every steam page is a different account, some in different languages.
Click your username, top right of the Steam Client, then click purchase history, and make sure nothing's fucky.
I got this fuckery:
Who the FUCK are these twats?!?!