lag, v.³ — Green’s Dictionary of Slang

lag v.³

[? fig. use of lag v.¹ (1), i.e. ‘pissing around’/‘piss on’]

1. to talk repetitively and tediously.

1956		‘Charles Raven’ Und. Nights 166: He certainly was one to lag was Andy Andrews. He used to talk to me by the hour about his ambitions.
2000		J.J. Connolly Layer Cake 99: If you get captured by Mickey on a bad night, when he’s had about ten pints with chasers, he’s lagging, all Queen and Country, up the Union jack, he’s a right pest.

2. (Aus. Und.) to inform.

1953		J. Franklyn Cockney 162: Should there be black eyes and the like to account for, it is a strong point of honour to let the method of their acquisition remain a mystery to interested adults. To ‘lag’ in this manner is to invite ostracism or worse.
1983		R. Aven-Bray Ridgey-Didge Oz Jack Lang 35: Lag Inform.

3. (also lag off) to shirk one’s duties.

1993		S. King Dolores Claiborne 17: And if you lagged off, she was apt to catch you. She didn’t watch every time you beat the welcome mat, but lots of times she would.
1997		L. Pettiway Workin’ It 200: I started lagging in school.

4. (S.Afr.) to laugh.

2005

A. Lovejoy Acid Alex 162: I was going to lag it off.

take lag (v.)

(W.I./UK black) to criticize, to attack verbally.

1956

S. Selvon Lonely Londoners 74: When Ma not there Tolroy used to take lag on Tanty left and right for coming to London.