Would you believe that a pair of legs has enough power to light up 3-60 watt light bulbs?

It is said that an average club cyclist can output about a hundred watts for several hours straight. 180 watts, for say 2 hours, would be a tougher standard but definitely achievable.

I've seen pairs of legs that light ME up.

Simple 500W Bicycle Generator - Run 220V Bulbs, Halogens, Drill Machines or Grinders   https://youtu.be/7B0HHGVuzcA

Most people can output 240 watts for a few seconds, Trained cyclists can do it for a lot longer

Sure:

I can push 1000W for a brief moment. Even that would light up more than 3 60W bulbs. I believe the sprint specialists manage more than 3000W. 

Thing is, for how long? 

A pro rider would be able to keep 4 bulbs going for several hours, but then he’s done for the day.

This article states that a reasonably fit person can power their entire house for 24 hours.  Quote, "One bicycle could potentially provide a small village with electricity if each household spends on hour per day pedaling the bike, and in such an environment where power is a more precious commodity, finding a willing cyclist would probably be easy to find 24 hours a day."  https://www.ecohome.net/guides/1192/60-minutes-on-...

ONE HOUR per day!  Pedal Power.   

Sure thing. There is a pedal operated generator selling in Amazon that is advertised to put out 50 watts. A person that is in good shape can generate a lot more electricity with a more powerful generator.