To explain this, in Legacy of Time, you go to Shangri-La. There, you meet Ghengis Khan. When you walk the underground passages of the temple, you can climb up just behind him. If you do, he turns around and punches you back down the ladder. Arthur will then appropriately speak the immortal line.
Here, skip to about 3:40. Also, pretty much anything Arthur says.
(when trying to approach a person with their own Chameleon guise): "Can you imagine how that person would react if an exact mirror image walked up and said 'Hi!'...Well...I guessyoucan."
That Non-Standard Game Over in Buried In Time, where two castle guards literally drop a cow on you if you take too long climbing the tower to the keep of Chateau Gauillard. The best part? The whole scene is a Shout-Out to Monty Python and the Holy Grail. Arthur even quotes the famous "Elderberries" line a little ways back while on the castle parapet.