child,
toddler, teenager, teen (informal), adolescent, youngster, tot (informal), tyke,
young'un (informal), sprog (UK, slang)
tease,
joke, rib (informal), poke fun at, make fun of, mock, ridicule, pull somebody's
leg (informal), yank somebody's chain (US, informal), josh (US, informal), rag
(dated)
fool,
trick, delude, hoodwink, con, mislead, deceive, bamboozle (informal), have on
(UK, informal)