This actually happened yesterday(on my birthday nonetheless). I was playing the Battle Arena in Emerald and was at a particularly high streak(The battle I lost at was #52), and I was actually not doing too bad, I wasn't even that nervous!
After Battle 50 and 51, I fought against a trainer who first sent out a Gyarados. Seeing as my team was Gengar/Salamence/Tyranitar, I was a bit concerned, but never-the-less, Gengar OHKO'd Gyarados with Thunderbolt. Feeling a bit more confident with myself, the trainer sends out a Dewgong. My first thought was "Eh, thunderbolt it."
And then it happened.
That Dewgong's quick claw had activated, and it had used Sheer Cold on me. Bam, Gengar was done. Starting to feel nervous, out went Salamence who was going to try to hit it hard with Brick Break. Again, it's quick claw activates and sends a crit Ice Beam my way. Out goes Salamence. Now extremely nervous, I sent out Tyranitar, who was going to try to Rock Slide it. Sure enough, Sheer Cold hit me one last time, ending my streak.
I have never felt so mad in all my years of playing Pokemon. I was almost ready to throw my Gameboy at the wall before I put it down on my bed and instead hit my table extremely hard with my fist. I've had bad moments playing Pokemon, but this, this took the cake.