1) To be really good.
2) As replacement to okay or great.
Note: Usually said with half-hearted meaning or sarcasm OR with little or no interest in the subject of the conversation.
Example 1
Boy: Sir, is this alright?
Mr. Lowis: Yeah proper smickles
Example 2
Boy: How would you answer this question sir?
Mr. Lowis: If you need to ask that after all these lessons you are clearly not paying much attention.
James L.: Sir it's easy! You're just stupid!
Mr. Lowis: Laughter
Boy: So would it be alright if I answered it like this?
Mr. Lowis: Yep, proper smickles.
Standing Ovation
A disease in which causes the ankles to shrink at an alarming rate. There is not yet a cure to Smankles but there has been speculation about how eating green apples will cause someone with Smankles to turn cannibalistic and hunt down large dingos, and eat the leader of the pack to become alpha. They then adopt the properties of the dingo and become the most dominant dingo. Smankles is fatal just like aids after one chooses to eat green apples and win over the dingos.
Man, I just got diagnosed with Smankles and now I have the overwhelming urge to eat green apples and go to Africa to take down the strongest dingos.