Akademik

с жиру лопаться
С <OT> ЖИРУ ЛОПАТЬСЯ/ЛОПНУТЬ highly coll, derog
[VP; subj: human; pfv past is not used in the affirm; more often this WO]
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to get very fat (usu. from inactivity, an idle life style):
- X с жиру лопнет{{}} X will become (be) a tub of lard;
- X will be (get) as fat as a pig;
- X will be (become) as big as a house (a horse, a barn).

Большой русско-английский фразеологический словарь. — М.: ACT-ПРЕСС КНИГА. . 2004.