WordNet (r) 3.0 (2006):

pink slip
    n 1: official notice that you have been fired from your job
         [syn: dismissal, dismission, pink slip]

Moby Thesaurus II by Grady Ward, 1.0:

23 Moby Thesaurus words for "pink slip":
   cashiering, conge, deposal, discharge, disemployment, dismissal,
   displacing, drumming out, firing, forced separation, furloughing,
   layoff, removal, retirement, surplusing, suspension, the ax,
   the boot, the bounce, the gate, the sack, ticket, walking papers