друг ‘friend’ (genitive: дру́га)
дружо́к = друг + diminutive suffix (genitive: дружка́)
дружо́чек = дружо́к + diminutive suffix = друг + two diminutive suffixes (genitive: дружо́чка)

Both дружо́к and дружо́чек can be used either as an excessively familiar form of address (e.g. Что же ты, дружок/дружочек, вздыхаешь? ‘Why are you sighing, my dear friend?’) or to refer to a friend (or to a boyfriend) tenderly or ironically (e.g. Она была там со своим дружком. ‘She was there with her boyfriend.’)