Mon Oncle wears a monocle

So I was thinking about monocles the other day, and found this at Wikipedia:

It is a myth that wearing a monocle is uncomfortable. If customised, monocles could be worn securely with little effort. However, periodic adjustment is a fact of life for monocle wearers to keep the monocle from popping.

I'm not sure I believe that.  It seems like to keep it in place you'd have to keep a perpetual scowl on your face.

I still think they're impractical.