I have one planned that will take up my whole back probably.   
It will read, in traditional Sans Serif 74 point font:   
"In the Ferrari and Jaguar switchin' four lanes,   
top down yellin' out money ain't a thing.   
Bubble hard in the double R flashin' the rings,   
With the window cracked, holler back,    
MONEY AIN'T A THING."   
The last part will be almost like a tramp stamp along my lower back.