What is the weirdest rule interaction you've ever actually witnessed or been part of during a match

[EventHorizon]

Watched a match end in a bizarre technicality neither player nor the referee had ever seen invoked before, took twenty minutes of rule book checking to confirm the actual ruling

[CodeOracle49]

Witnessed a match decided by a rule combination so obscure the officials had to look it up mid game, never seen anything like it before or since

[NoLimitsOscar42]

Was part of a match where a completely unprecedented situation forced an on the spot ruling that later actually changed the official rule book going forward