"Sizing up" means that you are judging the size of the situation. Size is how large or small something is. You're trying to decide whether it's a big situation or a small one.
They are sizing you up.
It's sizing someone up - it means to take their measure, to analyze them and decide what sort of person they are, how they're going to act, that sort of thing
Sizing Up the Senate was created in 1999.
Face up to a situation and not run away.
House Hunters - 1999 Up-Sizing was released on: USA: 20 July 2008
Wire Sizing Amps
Shaken up means to be nervous or in a weird situation.
My House Is Worth What - 2006 Sizing Up Smart Choices was released on: USA: 23 August 2009
It means you are a little bit mad and tired of the situation that is going on right now... "I'm fed up with this situation" I'm getting tired if this situation and just want to be done with it; over whelmed of the situation
sizing patterns.
sizing button
'Snacking' is close, perhaps you mean 'down-sizing'...