Irrepressible

Adjective

 * 1) Not containable or controllable.
 * 2) *1858, Charles Dickens, Nicholas Nickleby,
 * "...here the two friends burst into a variety of giggles, and glanced from time to time, over the tops of their pocket-handkerchiefs, at Nicholas, who from a state of unmixed astonishment, gradually fell into one of irrepressible laughter...

Adverbs for Irrepressible
obstreperously; riotously; uproariously; curiously; vexatiously; alarmingly; obviously; wantonly; mischievously; garrulously; independently; absolutely; offensively; restlessly; boisterously; noisily; feverishly; hysterically; violently; hot-headedly; fanatically; impulsively;  disagreeably;   unbecomingly; strangely; blatantly.

Thesaurus
abandoned, beaming, beyond control, blithe, blithesome, boisterous, breachy, bright, bright and sunny, bubbling, buoyant, cheerful, cheery, contumacious, defiant, ebullient, effervescent, elated, enthusiastic, eupeptic, euphoric, exalted, exhilarated, flushed, fractious, genial, glad, gladsome, glowing, go-go, happy, high, hopeful, immoderate, in good spirits, in high spirits, incontinent, incorrigible, indocile, indomitable, indulgent, insuppressible, intemperate, intractable, laughing, lax, licentious, loose, nonrestrictive, obstreperous, of good cheer, optimistic, out of control, out of hand, permissive, pleasant, radiant, rampant, recalcitrant, refractory, reinless, resistant, resisting, restive, rhapsodical, riant, riotous, rosy, sanguine, sanguineous, shrewish, smiling, sparkling, sunny, unbiddable, unbridled, unchecked, uncoerced, uncompelled, unconstrained, uncontrollable, uncontrolled, uncurbed, unforced, ungovernable, ungoverned, uninhibited, unmalleable, unmanageable, unmastered, unmeasured, unmoldable, unmuzzled, unreined, unrepressed, unreserved, unrestrained, unrestrictive, unruly, unstoppable, unsubdued, unsubmissive, unsuppressed, wanton, wild, winsome

Etymology
From.