Green’s Dictionary of Slang

(US) a mild excl. of annoyance.

1957		F. Kohner Gidget (2001) 92: Oh, crum, I forgot my bag.
1966		A. Harrington Secret Swinger 27: Oh, crumb. Let’s dance then.
1972		M. Rodgers Freaky Friday 58: Oh ook, oh cripes, oh crum, what to do now?