Is it ensure, insure, or assure?
mid-15c., from Medieval Latin scribillare, diminutive of Latin scribere "to write" (see script (n.)). Related: Scribbled; scribbling. The noun, "hurried or careless writing," is 1570s, from the verb.
To modify a data structure in a random and unintentionally destructive way. "Bletch! Somebody's disk-compactor program went berserk and scribbled on the i-node table." "It was working fine until one of the allocation routines scribbled on low core." Synonymous with trash; compare mung, which conveys a bit more intention, and mangle, which is more violent and final.