sport with
謔 centers on playful, teasing interaction: joking, bantering, or sporting with someone in a light-hearted way.
謔 combines 言 (speech) with 虐, which likely contributes the sound and may suggest playful or teasing talk. The exact historical development is uncertain.
The speech radical 言 beside 虐 (which can suggest harshness) creates a picture of words used in a teasing, playful way—sporting with someone through banter.
For ギャク, imagine a playful 'gyak' sound as someone teases a friend: the invented sound 'gyak' cues ギャク while the speech radical hints at joking.