blouser, v. — Green’s Dictionary of Slang

blouser v.

[Fr. blouse, a jacket; thus to cover with one’s jacket, to secrete. Ware suggests that the use is xenophobic, such a jacket would ‘cover over an honest Englishman’s waistcoat’]

to cover up, to hide.

1881		press cutting in Ware (1909) 36/1: The Army is warned that the clergy will try to ‘blouser’ or mislead them [...] while all the while professing interest in the Army’s holy labours.
1909		J. Ware Passing Eng. of the Victorian Era.