Whether it was because of the result, the way the game was played or simply the teams that were facing each other (any reason why you consider it bizarre).
For me the strangest/bizarre matches were the matches between national teams and clubs:
Boca Juniors Vs. México
Bayern Vs. Netherlands
Loma Negra (Argentine Club) Vs. URSS
Atlético Socoraba (Brazilian Club) Vs. North Korea
I once played in a game where the penalty taker got fouled on his run up to take the penalty and it was genuinely one of the funniest things I have ever seen