ho (interj.) Look up ho at Dictionary.com
exclamation of surprise, etc., c.1300; as an exclamation calling attention or demanding silence, late 14c. Used after the name of a place to which attention is called (as in Westward-Ho) it dates from 1590s, originally a cry of boatmen, etc., announcing departures for a particular destination. Ho-ho-ho expressing laughter is recorded from mid-12c.
ho (n.) Look up ho at Dictionary.com
by 1993, American English slang, representing a ghetto pronunciation of whore.