I was really stuck trying to make a gamertag, so I opened a sticky note on my desktop and randomly pressed a load of keys.
I got "MyNameIsLee" And stuck with that.
Before that, Fr0sTb1t3z, lulz. For that, I thought Frostbite was good. Taken. Muddled up the word with 1337 shiz and got that.
GingerNuts? - I didn't actually use this for a gamertag. But, honestly. I'm not ginger, nor do I have ginger testicles. The tag was just because I liked the cookies "GingerNuts"
Pwned.