I had Black in SP242 BNRKQBNR, where my opponent opened 1.O-O-O, and commented, 'What a funny first move! LOL!'. I had just finished the game described in 'Losing Streak', where I played 1...O-O-O!?, followed by a dubious idea. For this next game I decided to take a different road and to avoid castling for as long as possible.
The next moves were 1...e5 2.e4 a6 3.b3 b5 4.d3 Nc6 5.f4 f6, reaching the position shown in the top diagram. At some point during this sequence -- with 2...a6 & 3...b5 played to 'take advantage' of my opponent's early castling -- I realized that I had forfeited the possibility of castling 1...O-O-O, and would have to find another way to keep my King safe.
The next five moves were 6.Nc3 Bd6 7.Kb1 exf4 8.Nce2 Nge7 9.Nh3 Ng6 10.Qf2 Qe6, reaching the position shown in the bottom diagram. White is temporarily a Pawn down, but its recapture is guaranteed.
Instead of recapturing the Pawn, White went for a real sacrifice with 11.g3!. After accepting it I tried to get some counterplay with ...c5 and ...c4, but my opponent played d3-d4-d5, locking the Bishop on a8 out of play. By the time I decided to castle ...O-O on the 19th move, White had complete control of the center. The Kingside attack on the open g- & h-files was quick and decisive. When I resigned on the 36th move, material was still equal, but White was preparing an invasion that would net a few Black Pawns.
The castling choice in chess960 is often a difficult decision. Ignoring the common sense option can be a path to quick defeat.