Say the prime (saytheprime.com)We’re attempting to get a collection of humans to say every digit of the newly-discovered (and currently largest-known prime number) Mersenne prime M136279841, and hope to achieve this before another larger prime is discovered.
Dream argument (Wikipedia)The dream argument is the postulation that the act of dreaming provides preliminary evidence that the senses we trust to distinguish reality from illusion should not be fully trusted, and therefore, any state that is dependent on our senses should at the very least be carefully examined and rigorously tested to determine whether it is in fact reality.