on the button (adverb) absolutely: certainly, without question
Sinonime: babyish, babylike, callow,
foolish,
green*, immature,
inane,
inexperienced, infantile,
irresponsible,
jejune, juvenile,
naive,
petty,
ridiculous,
silly,
trivial, unfledged, ungrown,
weak,
youngAntonime: adult,
mature