[Raak] Not an allergy.
[cfm] There are two words on the card. The answer is not an identifier of the group itself, but a particular characteristic possessed by all members of that group.
[CdM] Yes, the vegetable reference is to a particular species in the vegetable kingdom.
[Chalky] Not users of walking sticks, (or users of wooden crutches, or members of the Long John Silver Admiration Society with wood peg legs, or of the Geoorge Washington Emulation Society with wooden false teeth for that matter either).

You know how it is, you get an idea and either ask it directly or give it away for someone else

[INJ] Ruled out by the Brassica comment, I fear.

[INJ] Nope, due to to the Brassica comment as CdM indicates. However, the audience sits up in rapt attention at the nature of the response, and a few of them even applaud at the turn of events.