Letter often used by morons where S would be more appropriate. Sometimes denotes a plural, but may be included for no clear reason whatsoever. Tends to accompany aLtErNaTiNg cApZ and the substitution of letters with other ch4r4ct3r5. See also gay speak.
When typing "xoxox", or hugs and kisses, a "z" may be inserted to denote some other form of affection. The "z" action is up to your imagination to fulfill!
