A very common unit of energy in Astronomy is erg. There are stellar sources that emit up to 1040 erg/s (or even more for galaxies). But, how could we understand “how much” erg is? An interesting and funny example is given in the Wikipedia [1]:
“An erg is approximately the amount of work done (or energy consumed) by one common house fly performing one “push up”, the leg-bending dip that brings its mouth to the surface on which it stands and back up”
Will you ever forget that ?
[1] Erg, https://en.wikipedia.org/w/index.php?title=Erg&oldid=668792761 (last visited July 28, 2015) – after ref. 2: Filippenko, Alex, Understanding the Universe (of The Great Courses, on DVD), Lecture 44, time 24:30, The Teaching Company, Chantilly, VA, USA, 2007