Green’s Dictionary of Slang

1. (Irish) a male copulator [the threading (i.e. thread v.¹ (1)) movements of weaving].

1795

‘Shale’s Rambles’ in A. Carpenter Verse in Eng. in 18C Ireland (1998) 504: So now you maids that love the trade, and now has took the notion, / Apply to me, we’ll soon agree, I’ll put your loom in motion, / [...] / To raise a twill with art and skill, for I’m the Lurgan weaver.

2. (US) a poor driver who weaves from lane to lane along the road.

1960		AS XXXV:4 312: For a long time we have heard of the weaver, the driver who shifts from lane to lane in driving.
1973		Tel. (Brisbane) 13 Sept. 30/1: Then we have the weaver, who careers from lane to lane, passing other cars right and left .
1998		‘Weavers’ on MotorCity 🌐 Weavers are the single biggest annoyance (and danger) on Bay Area roads today. Case in point: the I-280 commute south from SF to San Jose every morning.