"young mammal before it is weaned," late 14c., agent noun from suck. Slang meaning "person who is easily deceived" is first attested 1836, American English, on notion of naivete; the verb in this sense is from 1939. But another theory traces the slang meaning to the fish called a sucker (1753), on the notion of being easy to catch in their annual migrations. Meaning "lollipop" is from 1823.
To victimize or dupe someone: if I can sucker him into drawing first (1939+)
[origin uncertain; perhaps fr the sucker, a fish supposed to be easily caught; perhaps fr the notion of an unweaned and relatively helpless creature, as suggested by an earlier sense, ''greenhorn, simpleton'']