Green’s Dictionary of Slang

to loiter aimlessly, to ‘hang about’.

1758		E. Raper Journal 18 Dec. in Receipt Bk (1924) 20: Nothing but Uncles and Apothecarys, muzzed at home [OED].
1779		Mme D’Arblay Diary and Letters (1904) I 177: ‘If you but knew,’ cried I, ‘to whom I am going to-night, [...] you would not dare keep me muzzing here!’.
1794		J. Williams Parental Didactics 18: And that high royal corps snug and sublime, Who muz majestic in the court ycleped Crane [OED].