AIBU to ask: what is a smugest?

[Oleoleoleoleole]

As promoted by Mumsnet. ("Your smugest DIY wins".)

Most smug.

Most smuge, surely?

Typo for smuggest?

I never even knew I had a smugest, much less that it was a single handed winner, until Mumsnet repeatedly told me about it. So, now that I am aware of my champion's existence, I would like to know what it is.