Swizz

The boy in Peter Shaeffer's play EQUUS calls his doctor this. One dictionary says "a Brit", but that
doesn't make sense. Please enlighten me! Thanks.

Here's another definition, though it doesn't seem to fit the context either. Peter Scaeffer is English.
The on-line English to American Dictionary;
swizz n. This is a small-scale swindle or con. If you opened your eight-pack of KitKats and there were only seven, you might mutter "that's a bloody swizz". If you discovered that your cleaning lady had been making out large cheques to herself over a ten year period, you'd be inclined to use stronger wording.