If you don't know 100% what you want, don't get a tattoo, for gods sake don't take suggestions.
This goes 1,000,000 x for sleeves.
If you don't know what you want, why are you thinking of getting one at all!
I bought some tattoo sleeves off ebay for around £3.00. Buy those and walk around. See how you feel.
Big Bang Fail
I was discussing tattoos with my girlfriend yesterday, she said I should get an I/O plate tattooed on my arm, I said I'd get "USB3 Compatible" but then she pointed out that USB 3 will be out of date at some point lol
I deciced I could just get a button that said "Press Here to Turn Me On"
You might get an idea from here:
http://forums.overclockers.co.uk/showthread.php?t=18004711
Just remember, you'll have it for life.