I suspect that some slang in the English spoken by Scots originates from Gaelic, but seriously, no one is going to expect you to understand uniquely Scottish expressions that even English people don't recognise. You could learn a few common Scottish English local expressions which I am sure would endear you to people in Scotland. Have a look here: http://www.scottish-at-heart.com/scottish-sayings.html

haha I think watching the film Trainspotting may help !!!