In play, in jest.

in jest, in mockery.

in sport: in jest, jokingly; for fun or diversion, not seriously or in earnest. Now somewhat archaic.

In play.

Jestingly, in jest, frivolously.

The opposite of earnest or seriousness; trifling sport, fun. Chiefly in phrases, as in jest: not seriously, without serious intention, in joke…

In a manner calculated to amuse or entertain; in or with jesting words or speech; wittily, satirically; facetiously, mischievously. Now rare.

In a jesting manner; by way of joke or merriment; in jest, not seriously.

In sport or jest; jokingly.

In a sportful manner; playfully, jokingly.

Without serious purpose or intent, mischievously; (also) with unpredictable results, capriciously, erratically.

for fun: in order to amuse oneself and not for any more serious purpose. Hence in extended use: easily, at will.

in a flippant manner.

As postmodifier: not serious or in earnest; causing or designed to cause amusement, risible.