Well... my story probably won't help you much due 
to unique circumstances, but it is amusing 
nonetheless.

Katsucon this year got snowed in, savvy?  
(*giggles madly* Sorry... Pirates of the 
Carribbean is my newest obsession.)  Basically, 
everyone was trapped in the hotel for an extra 
two days, including the guests.  The particular 
guests this story is about are Duel Jewel, the J-
Rock band.  Now, Katsucon staff had pretty much 
kept them under heavy guard for the whole con, 
never letting any fangirls near them.  But during 
the little extra con time, there were merely 
several hundred people in the building, rather 
than several thousand.  On Monday night they came 
out of hiding and decided to get drunk at the 
hotel bar.  No body-guards this time- they were 
swamped with fangirls.  And enjoying every minute 
of it, so they were. *laughs*  And that's how I 
got my Duel Jewel autographs. ;-)

The other autographs I have are from Hiroyuki 
Morioka, from last year's Otakon.  His (rather 
underattended panel) ended early, and I merely 
wandered up front and asked him to sign some 
cels.  The con staff there sort of shrugged, they 
didn't see any harm in it.  So we had a nice 
little conversation about cels (through the 
translator, of course) as he signed.