Having a cock the size of an electron.
An electron has no definite size and a mass of approximately 10^-34 Kg. Approximately 0.0000000000000000000000000000000006 Kg.
You see where I'm going with this ...
Jimmy's winkie was so small that Felicity described him as an electron cock.
"Let's go poke fun at the physicists for all having electron cocks!"