As nouns the difference between necker and fecker
is that necker is neckerchief, especially from the scouts or necker can be someone who kisses; a kisser or necker can be someone or something with a certain type of neck while fecker is (ireland) fucker.
necker
English
Etymology 1
Shortening of neckerchief
Noun
(
en noun)
neckerchief, especially from the Scouts
Etymology 2
From the verb neck
Noun
(
en noun)
Someone who kisses; a kisser
* 2008 , Don Malarkey, ?Bob Welch, Easy Company Soldier: The Legendary Battles of a Sergeant from World War II
*:We all ate at the Liberty Grill, and then Bernice and I drove her family's Pontiac upriver, to a hill overlooking Tongue Point, where plenty of neckers were fogging up the windows.
Etymology 3
From the noun neck
Noun
(
en noun)
someone or something with a certain type of neck.