Where Observation Can Affect The Outcome

(Our science teacher is performing a demonstration on a mini Tesla coil which creates little sparks. As he is doing this, two girls are chatting to each other in background.)

Teacher: “As the metal rod is positioned closer to the electrified coil, we can observe tiny…”

(He turns to the girls chatting to stop them talking.)

Teacher: “…ladies!” *pauses for a second, realising what he just said*

(The classroom bursts into laughter.)

Student: “But isn’t that illegal, sir?”