"OMG Bill Kaulitz is soooo Smexxiful!"
"Whiplasher Bernadotte is sooo efffin Smexxiful"
"There's this Smexxiful Guy named Bill Kaulitz"
"Smexxiful? as in.. Bill Kaulitz?"
A stupid version of the word "sexy" with the suffix "full" added on to it, probably by someone with way too much time on their hands in a failed attempt at individuality.