What does this shiet mean

at the drop of a hat

See link below.
A question for you: what is a "shiet"?

I think it's Scottish for "excrement". They said it every other word in Trainspotting. I thought it was spelled "****e", but I guess not.

It absolutely is spelled "****e", cf. "gob****e", another quaint Scots/Irish term of abuse.

Maybe the 'shiet' version is a dialectic difference - hehe. Or it could simply be a reflection on the educational standards attained by those in 'trainspotting'.