stibber-gibber, n. — Green’s Dictionary of Slang

stibber-gibber n.

[Beale (DSUE, 1984) suggests a corruption of two typical contemporary names, Stephen and Gilbert, generic for lying clerks]

a habitual liar.

c.1561

Awdeley Fraternitye of Vacabondes in Viles & Furnivall (1907) 14: Protour [...] This is a stibber gibber Knaue, and doth fayne tales.