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Oh, him? He’s harmless. Part of the free speech movement at Berkeley in the sixties. I think he did a little too much LDS.
— Kirk • Star Trek IV: The Voyage Home

Behind the line May contain spoilers.
Our reading
An editorial interpretation.
The speaker explains someone's behavior through a casual story about activism and drugs, while insisting that he is harmless. The mistaken-sounding abbreviation 'LDS' adds another comic complication. The explanation works as improvised reassurance, without establishing whether the story being offered is true.
Context reviewed