Ш-71

ШИШКА НА РОВНОМ МЕСТЕ coll, derog NP usu. subj-compl with copula, nom or instrum (subj: human fixed WO

a person who exaggerates his own importance ( usu. said in refer, to s.o. 's position, office)

a small fry who thinks he's a big fish

(said ironically) big cheese big shot.