Three Tunnels
Riddle: Spencer wakes up in the middle of a forest. A few seconds later, a witch and three magic tunnels–a red, a yellow, and a blue–appear in front of the guy. The witch tells Spencer, "Two of these tunnels will make you disappear forever, and the other one will send you back to your house. Listen to these clues VERY carefully,". Clue 1: Choose the red tunnel, and you won't not disappear. Clue 2: It's a lie to say that the yellow tunnel isn't dissimilar. Clue 3: The blue tunnel doesn't have less in common with the red than with the yellow. Which tunnel should Spencer choose?
Answer: Spencer should choose the yellow tunnel. If he chooses the red tunnel, he will not NOT disappear; in other words, Spencer WILL disappear if he enters the red tunnel. We can therefore exclude the red tunnel. If he chooses the blue tunnel, he will also disappear; this is because the blue tunnel doesn't have less in common with red than yellow. In other words, the blue tunnel has more in common with red than yellow, so the blue tunnel will also make Spencer disappear. Choosing the yellow tunnel is the safest option because if it's a lie to say that yellow isn't dissimilar, the truth is that yellow IS different from the red and blue tunnels.
Source: https://www.riddles.com/11352
