To throw something casually or with a light toss.

The origin is uncertain, though it may be a variant of 'chock' or related to French 'choquer,' meaning to strike. It appeared in English as an informal word for tossing or throwing. The word also developed a friendly sense, as in chucking someone under the chin affectionately.

Past tense of fling: to throw something with force.

Probably from Old Norse 'flengja,' meaning to whip or flog, or related to Swedish 'flänga,' meaning to rush about. The word entered English with a sense of energetic, forceful throwing or movement. It has also developed the informal noun sense of a brief, carefree adventure.