Green’s Dictionary of Slang

slip n.1

[ety. unknown]

a counterfeit coin.

[UK]Greene Disputation Betweene a Hee and a Shee Conny-Catcher (1923) 64: He went and got him a certaine slips, which are counterfeyt peeces of mony being brasse, & couerded ouer with siluer, which the common people call slips.
[UK]Shakespeare Romeo and Juliet II iv: rom.: What counterfeit did I give you? mer.: The slip, sir, the slip: can you not conceive?
Jonson Epigrams 64: First weigh a friend, then touch and try him too, For there are many slips and counterfeits [F&H].

In phrases

nail up for a slip (v.) (also nail up for slips)

to reduce (through poverty) to using counterfeit coins.

[UK]Lyly Mother Bombie II i: I shall goe for siluer though, when you shall bee nailed vp for slips.
[UK]Marston Antonio’s Revenge I ii: Your nose is a copper nose, and must be nail’d up for a slip.
[UK]Austin Meditations (1635) 108: But (here) they Naile him up, for a Slippe (a Brasen Counterfeit;) one, that did but say hee was a King [OED].