Why even bother trying to offer any help when people are intent on being so sarcastic!!
Yes, I know my studs are on 24 centers but maybe not everyone knows that an exterior wall can have such spacing. If they didn't know this, they might well take Steve K.'s advice and start driving nails in the wall without even realizing that maybe the studs could very well be at 24" centers. A good rap with the knuckles will tell you when you are getting close to a stud. If you find that that they seem further than 16" apart than you can probably assume they are on 24" centers.
Funny how a harmless piece of information such as what I provided in my previous post could invoke such a nasty reaction.