For the people who want this but don't live in the US:
Use a proxy (ztunnel worked for me, uncheck remove scripts) and visit https://shop.popcap.com/zombiemouth/redeem if you cannot access the offer.
Yes.
Quote from http://imgur.com/a/g0UeC#3:
Check back at 6PM CT for the code to obtain the "Stinger Missile" customization for Gaige the Mechromancer!
http://imgur.com/a/g0UeC#3
Details on the Zer0 spooky skin
(doesn't work as of right now)
http://imgur.com/a/g0UeC#4
Details on the mechromancer spooky skin
Twitter:
PC: C3WT3-W96BK-K6JTB-JB3JJ-3J6CS
Xbox 360: WTKJJ-CW59K-RHRJ6-W6BB3-KWZT9
Playstation 3: KTWJT-6TK5T-JCCCB-ZJ5B3-6HTXK
Facebook:
PC SHiFT Code: WT53J-Z5WWB-3W5K3-HJWJJ-XBJ3H
Xbox 360 SHiFT Code: 5JWTB-6FCS5-FHXT6-56BTJ-WBWFT
PlayStation 3 SHiFT Code: 5J533-63HTC-W633B-3BTJB-9C3FX
Twitter:
PC: KBCB3-THXT5-CX3TB-3TT33-TW5ZS
Xbox 360: CJ5JJ-TC59K-FSR3X-WRBJB-BFXFR
PlayStation 3: CJCT3-K3C5J-TKKWB-ZBWTJ-JW3C9
Facebook:
PC SHiFT Code: 535TB-FK5K3-3W5KJ-SBK3B-R6RRX
Xbox 360 SHiFT Code: 5BKBT-WF5H5-XSFJF-KX3B3-F5SJS
PlayStation 3 SHiFT Code: 5BKBT-5BHTC-WXJJ3-JBBBT-KZX3B
Completely agree with Severose everyone says Thanks OP! but someone else posted the codes and updated the original post. Oh well, as long as people make use of the keys and are thankful, right?