mamón
sucker
mama
breast
+
-ón
augmentative suffix
A mamón is a sucker, which can be thought of as someone who excessively (-ón1) breastfeeds0 (mama0).
noun
- suckerA person who is annoying or irritatingEse tipo es un mamón, siempre molestando a los demás. // That guy is a sucker, always bothering others.