Well the funniest thing that happened was when I just started Bass and it happend around 3-4 years back.

So I got my bass + amp + tuner + method book

I thought that its wise to tune my bass first
So I attached the tuner (which picks up vibration) on the headstock
and started tuning to the bass standard tuning which is EADG

But at that time I knew nuts about the tunings and stuff... All I know is EADG (From the TABs In the Method Book)

And guess what? I read the TABs Upside Down.. 

You guessed it,
I tuned the strings Upside Down (GDAE)

The E and A strings survived the extreme high tension, But when it was till the D string, I remembered that when I achieved a near perfect G (Just a step more towards A) the string just gave way and just sprang out violently    

And worst still, I still did not realise my mistake and thought that I tuned it An Octave too high. So I tuned the E A and G string (D String snapped) down an octave sill in the wrong tuning (Still tuned upside down)

But there is no tension. So I concluded that there is a problem with the bloody tuner. So I got my Rant Speech ready and marched back to the music shop the next day.

It all ended when I explained what happened to my current ex-teacher and he just blew out laughing his ass off (Literally)

Me <

And when he explained my mistake

I changed from  to

And because I "Brightened" his day, He gave me a new pack of D'addario free of charge and told me not to mess with anything until I know enough.
The moral of this true story is : Only mess with stuff if you know what you are doing

Damn.. I snapped my high E string on my Acoustic today.....
Freakin' whiplash left a nasty mark on my right hand....... Tuning it and then *SNAP*

Sigh...... need to re-string it anyway.....