Slipstring

Every promise that thou therein dost utter, / Is as sure as it were sealed with butter, / Or a mouse tyed with a threed. Every good thing / Thou lettest even slip, like a waghalter slipstring.

Goinfre: m. A wag, ſlipſtring, knaviſh lad; a merrie conceited whoreſonne, a notable good fellow, an excellent companion.

Well, slip-string, I shall meet with you.