"Oi" means "Hey!" It is used to get a person's attention, such as in "Oi, Geordie! Want to see something you've never seen before?" It is usually fairly understandable just from the context.
And it's "blusher," not "blushers." In "Expressing Yourself," Michael sings, "Who the hell cares if your blusher's [blusher is] a mess?"
Blusher is the powder rouge that women apply with a brush. It is called that just about everywhere that cosmetics are labeled in English. It's not a Geordie word.
"Bairn" is a word for "child," more specifically, a boy. It shows up in the Scottish ballad "The Great Silkie of Sule Skerry," listed as Child ballad #113. The lyrics are given here:
http://en.wikipedia.org/wiki/The_Great_ ... ule_Skerry
I have sung this song since I got a guitar and learned to play it in high school. I got the song from listening to Joan Baez.
"Sod" is a shortened form of "sodomite," as in a resident of Sodom, which, according to the Bible, was destroyed by God because of the people's licentious ways. In general, it is an equivalent of calling someone any one of a number of sexually tinged insults. "Sod off" is basically the same as "F**k off." Various forms of it are used in the show. For example, when Billy asks Debbie how she puts up with her mother, she says, "I don't have much of a sodding choice, do I?" And yes, somebody thought it was "sodden" because of how it's pronounced, but it's actually "sodding." When Billy hesitates to accept Mrs. Wilkinson's offer of private lessons, she says, "Well, sod you then. See if I care!"