What can you put in a bucket to make it lighter?

How to think about it

1. Anything with weight makes the bucket heavier, so the answer is an absence, not a substance.
2. The hint rules out helium, which is the joke answer for making things float.
3. What can you “put in” a bucket that is really a lack of bucket?
4. A hole lets the contents drain out, so the bucket gets lighter.

Why “a hole” is the answer

Putting a hole in a bucket means removing part of it and letting whatever is inside pour out, so the bucket ends up lighter. The riddle plays on the phrase “put a hole in”, which sounds like adding when it is really taking away. Helium is the usual wrong turn because it makes balloons rise.

Common wrong answers

• Helium. A bucketful of helium weighs less than air, but you cannot keep it in an open bucket, and the hint rules it out.
• Nothing. Putting nothing in changes nothing; the bucket stays the same weight.