goes to the House of Representatives to decide.
Something like 25% of the likely US voters said that they feared BOTH candidates.
If Johnson and Stein siphoned off enough votes in a close race things could get very interesting. Historically interesting.
I has happened a couple of times in US history:
https://www.quora.com/What-happens-if-presidential-candidates-cannot-get-the-required-amount-of-electoral-votes