Title text:
Highway engineers like Planck units because, like the speed of light, the energy capacity of a typical car's gas tank is 1.
Transcript:
Transcript will show once it’s been added to explainxkcd.com
Source: https://xkcd.com/3289/
Scientific notation is great and all but sometimes you just need a bunch of zeroes in the number to really hammer in how big/small something is.