You're best off getting a new tire, but I've had plugs on my bike before. It's an OK temp solution if you're not going to be doing any hard or long riding...
If you're gonna get a mushroom plug, the tire has to come off. You might as well just buy another one.
For a temp thing, I'd just get a regular one with some rubber cement and that'll work, but again, take it easy and check you're tire pressure regularly!

 

tires without plugs have been known to blow out. having a defect should only increase the probability of this occuring. why does this question even come up.

my bike and body are worth more than $200 to buy and mount a new tire.

i actually can not believe that a shop would plug a tire even at a customer request. with the capablility of doing 150 mph plus with ease it seems like a law suit waiting to happen.

 

Just out of curiosity, has anyone actually ever had one fail?

 

Take a look at these plugs...

http://cgi.ebay.com/ebaymotors/MOTOR...2em118Q2el1247