A term used in Scotland to describe the English. Derogative in a sort of in a tounge and cheek way. Their is probably a relationship with the word assasin or traitor going back to the times when the English lorded it over the Scotts. The word is used mostly between some Scottish people to describe the English.
When they do come into contact with an English person they may try to tell them that they are sassinacks. However most English people cannot understand the Scottish therefore, using a word like sassinack in conversation usually increases the look of bewilderment.
In Conversation between Scotts.
Wits that sasinack daen here in oor land.
In non Conversation between a Scott and and English person.
Ya sassinack away back tae where ye came fae, wurs ma haggis.