Green’s Dictionary of Slang

padded adj.

(US Und.) concealing contraband (stolen articles, drugs etc) on one’s body for removal from a shop, deceiving customs men etc.

[US]Jackson & Hellyer Vocab. Criminal Sl. 64: padded [...] To have swag concealed about the person in a neat, compact order so as to enable the thief to pass inspection.
[US]Irwin Amer. Tramp and Und. Sl. 140: Padded. – Having loot concealed upon the person, regardless of the bulk or amount of the loot.
[US]Goldin et al. DAUL 151/2: Padded. Having stolen goods or contraband secreted on one’s person. [Note: Drug smugglers, often disguised as uniformed messenger boys, board and leave docked ships after being padded with several kilos of drugs, usually taped about their bodies.].
[US]Ragen & Finston World’s Toughest Prison 811: padded – Having loot concealed upon the person.

In compounds

padded wall (n.)

(N.Z. prison) .

[NZ]D. Looser Boobslang [U. Canterbury D.Phil. thesis] 133/2: padded room (also padded wall) n. a strip cell with a camera, for ‘at-risk’ inmates.