In post chess or online chess i have never blundered away a piece.
In OTB chess i once blundered away a rook and, some years later, on another game, blundered away another one, almost in the same way: a bishop on the g5 square goes back and takes my rook on d2...
In blitz games i have made lots of blunders, over many years, but that doesn´t really counts, does it?...
I actually blunder less often online than over the board. Being at the club, I get knots in my stomach and somehow I don't see the position as well. In my first rated game I played OTB, I was so nervous that I actually moved the queen to a square where the knight could grab it. Now that's a blunder.
Multiple blunders in one game is no surprise. I get emotional after the first one, and that clouds my judgment, which then leads to further mistakes.
I have been playing and studying chess in a serious way the last four months, and it really pays off. Now I just see threats without having to look for them, and generally blunders are less hideous. Some grandmaster wrote that blunders never go away, but as you get better the reasons for them tend to be psychological rather than ordinary stupidity.
Of course, if I were watching t.v. while playing chess, I would fully expect to play a sloppy game.
Well there have been way to many for me to give details of just 1 particluar time. But while I am playin my chess games, I am also playing online poker (at times more than 1 table and more than 1 game), and I am also usually on IM with my girl. So I have made so many blunders that i try to just forget about them and just continue to play my game.
Whilst I tend to make more 'mistakes' OTB, simply because I don't have the same time-frame and capacity to analyse, my 'blunders' are much more common online, usually from when I approach a game that I haven't looked at in days and make a move too hastily - there isn't the same sense of progression and awareness that one has with an OTB game.
My worst blunder was probably when I once blundered away my queen online, but was so vacant-headed that I contined playing, blissfully unaware of my loss for a good 6 moves before suddenly to my surprise I became aware that there was no longer a queen on my side of the board, which was quite a shock to the system - especially as I could barely even remember making the move that lost my lady.
A queen and BOTH rooks.. same move. (made an awful move that managed to hang one rook with check, and then allow the queen to take the next rook with check next move, and then skewer the queen with the final check.
I had this one game where I kept on falling into a bunch of traps trying to avoid all of the obvious ones. I blundered away several pawns and a rook within about 5 or 6 moves. It was the most traumatising experience of my life, but then again I don't go out much 
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1300-1670 back to 1380. yep, few blunders there. lost my queenin about 8 moves- for nothing.
ALL IN FUN THO
One of my weirdest games-OTB
I battled an 1100 and I was rated 1424, but lost two rooks for one knight when he had only 30 seconds left. Astonishingly, I won the game, by checkmate, not time!
I made bluders because I was doing a different thing while playing chess e.g playing online games. I think a better way to avoid blunders is to make sure that your focus is in playing chess.
The other day I was playing in an endgame up a 2rooks+bishop to 1rook+bishop. Well he put me in check, and I had 4 moves with my king. 3 were safe, and one lost me my bishop AND rook. I chose the latter and quickly resigned in anger.
Celebrate your triumphs and learn from your losses. The most important thing is to never make the same mistake twice. It's easy to toss aside a game where you blundered a piece, but if you go over the game and really analyze it thoroughly, the next time you reach a similar position, hopefully you will make the right move!
I made 20 blunders
I made 17 blunders u beat me by 3
L
skill issue
cry bout it
Once I forgot which way pawns capture so I blundered a queen... embarrassing. If anyone likes FREE awards, you have to join Merry Christmas Tournament. It is a 7 day game and trophies go to top 3 winners. Here is the link: https://www.chess.com/tournament/merry-christmas-tournament-2
I recently gave away my Rook and later Queen in one game... I like to believe that it is due to playing online (playing online, watching t.v., downloading etc...so not 100% dedicted to Chess)
Thought it might make me feel better to hear some other horror stories where pieces have been blundered away on multiple occasions in the same game.
Anyone?