Green’s Dictionary of Slang

crimp up v.

[SE crimp, to pinch]

(US) to toughen someone up by inflicting verbal and/or physical pain.

[US]Simon & Burns Corner (1998) 205: ‘Crimping ’em up’ is a local expression for the process by which the older kids toughen the younger ones, steeling them for the reality of Fayette Street with a thousand petty insults and savageries.