I remember once I was playing a festival out on the West Coast somewhere.  There was a cat there, harmonica player, that I would see him at my gigs from time to time when I would travel out to California.  He obviously knew a lot about the music and loved it.  One night he showed up and just jumped up onstage.  He started playing, face all scrunched up like he was getting down all the way...except he was doing more honking than playing.  It was rough on the ears.  Ouch.  I ended the song early and told him thanks for coming up.  He tookthe cue and went into the crowd.  I think he was just happy to have been up there for a little while.  

Haha! Yeah I see lots of harp player or I should say blues lover with an harp in their hands that always whant to play but can`t, they think that because they create sound that they create music, or because they found the right key then can just blow but they dont wich chord they play over! I think they just really want to be a part of the music but don`t realize that they ruin it, in a bar context I think its a good thing to let them play a song, they have 3 minutes of glorry and you tell them, just like you did, thank you and let them go, or ask if they don`t! That way you give them a good time and memory!

@Corey....ahahah nice...this reminds when I used to play djembe with my senegalese brothers in the clubs....it was the rule that somebody, as the stage was in front of the people (really little clubs), at a certain moment started to say....hey...give me that djembe!!...to all of us..no exception..one day was for me..the other day for my brother Makhtar..I want to play!!....or even worse...they started putting the hands on the djembe....off course all drunk people...  and I got so upset when this happened but mainly I didn't know what to do...sometime I just let them play on my djembe and after a while stay at game, say that they have played really good but at the end took my djembe back....in other cases I just said....NO...go away...and as these folks usually were drunk...well I had some problems....one said...hey...you're an assohole...djembe is an instrument for everybody...let me play...but at the end I was always safe as if I'm thin...it was true that my brothers were all high, tall and really strong!!! :DDD

This kind of things never happend to me when I played the guitar...

Yeah Corey, I feel your pain on this one. Some people don't seem to have a reasonable perspective on their own competence and abilities. If nothing else this lack of self-awareness is proven by watching just one episode of American Idol.

This brings up an important point about how people learn to play music: they learn best by playing with better musicians. I'm not saying you need to grin and bear it when an over-enthusiastic fan gets up and literally makes some noise - people pay money to hear good music (you). But it used to be more common for amateurs to sit in a bit with professionals, get their butts kicked, go off and woodshed for a while, and then do it again. It's all part of the mentoring process of exposing learners to performance situations in order to give them a sense of what is expected and what their practicing goals should be. This dude's problem is that he wasn't aware that it is a mentoring relationship, and as such you and he should have some kind of relationship...I mean, some kind of relationship other than the one he has clearly formed in his mind.

Anyway, it sounds like you dealt with the situation graciously. If it was my Irish-American ass in the same situation I would have been, let's just say, abrupt.

I love your lessons, by the way. I've been tearing up my old National for the past few months, leaving my other guitars to feel abandoned and confused. Yes, yes, I am a neglectful father where my guitars are concerned. Thankfully I am not so with my daughter.