Tutorial on how to change your gamertag to anything and troll your friends!
Proof:


Please Note that this will not change your gamertag using this glitch. This is used to have fun with and mess around with your friends!

Text Turorial:
1) Press the guide button and press right on the "right" bumper until you see "Profile"
2) Then click on "Profile" then click on "Edit Profile" after you have done that click on "Gamertag"
3) Click on "Enter New Gamertag"
4) Edit the gamertag to something that is not taken! Ex: example283748
5) Press on "Done." This will take you to where it says "Yes, use this gamertag" and "No, edit it"
6) Click on "No, edit it"
7) Now, change it to any OG Gamertag you want! Ex: Sniper
8) Press on "Done." It will say, "The Gamertag 'Sniper' is already in use."
9) Scroll down and click on "Get Suggestions"
10) After that has loaded up press B 2 times! It will say you can use that gamertag!
Have fun!