>>I Just Can't Help It. How did we get from re-sizing to sizing up?
>
>I'm not familiar with this expression - what does it mean?

this, I believe http://www.thefreedictionary.com/size+up - bottom

Verb 1. size up - to look at critically or searchingly, or in minute detail; "he scrutinized his likeness in the mirror"
scrutinise, scrutinize, take stock
examine, see - observe, check out, and look over carefully or inspect; "The customs agent examined the baggage"; "I must see your passport before you can enter the country"