BUBRARY> (defclass my-class () ())
#<STANDARD-CLASS MY-CLASS>
BUBRARY> (defmethod print-object ((o my-class) stream) (print "my-class" stream))
#<STANDARD-METHOD PRINT-OBJECT (MY-CLASS T) {BFA0A19}>
BUBRARY> (make-instance 'my-class)

"my-class" 
BUBRARY>