--
Vants/ Pl. vantsn means bedbug . I have never heard it used pejoratively for an adult , but I am sure it is possible . My father used to call me " kleyne vantsl " which would be an affectionate term for "scamp" or "rascal" .
Vonts pl vontsn or vontse pl. vontses is whisker, one side of a mustache or a mustache , vontselekh being animal whiskers. ( Bienfeld dictionary)
The reason for the confusion on spelling is that in " Tote-Mome loshn" the a is pronounced as an " o" . So , Vonts and vants would be homonyms. I noticed that Jews in London who were not all from Bessarabia/Moldava/Romania where that pronunciation was prevalent still said "Shobbos", "Khole" (Challah ) and "Khosn-Kole" ( Khosn-Kale-bride and groom) . but also the Polish " baygl"
instead of "beigel" . Gey veys! ( who knows why lit. Go, know ) So the writer may have heard the expression 'vonts" from a Bessarabian speaker or from someone who may have picked it up from a Bessarabian .
As for the theory that the writer actually heard "shvants" which is literally a tail but is vulgarly used to refer to the male organ and disparagingly used ( shvantz or dim. shventsl ) for a " stupid bastard" . ( Bienfeld dictionary ) .Interestingly , shvantsevate (vulg.) means "damn stupid" (Bienfeld )
I still go with the theory that the writer actually heard "vants" pronounced as "vonts" !
Henry H. Carrey