wag1
  
  v.
 (wags, wagging, wagged)
 (especially with reference to an animal's tail) move rapidly to and fro.
n.
 a wagging movement.
 
  Etymology
  ME: from the Gmc base of OE wagian ‘to sway’.
 
  
    
wag2
  
  n.
 a person who makes facetious jokes.
v.
 (wags, wagging, wagged)
 Austral./NZ play truant from (school).
 
  Etymology
  C16 (denoting a young man or mischievous boy): prob. from obs. waghalter ‘person likely to be hanged’.