I drop strange facts in the comments section sometimes.
Stuff like
"The stage before frostbite is called “frostnip."
and
"Before the term “bloopers” was coined, ‘out-takes’ were called ‘boners’."
@Despairagus that one's for you
I've received a bonuses ranging from .05-.50 cent sent my way in appreciation or accusation as a result.
One requester admitted that she exhaled her coffee through her nose because I'd caught her unaware.
I just do it because I do shit like that. It's definitely not worth the time involved for the occasional bonus but it does break up the monotony a little bit.