Shorthand for on primary key?
No there isn't anything similar to what you are asking built into the product. 

Standard SQL has the concept of a NATURAL JOIN that joins on common column names but SQL Server does not implement this and there would be no guarantee that any such names would correspond with the PK anyway.

It would be possible in theory for you to write some sort of script pre-processor or dynamic SQL code generator that did this if it was a massively important need for you.