Drögen
Drögen is a German adjective meaning "dry." It can refer to a lack of moisture, either literally (e.g., dry land, dry air) or figuratively (e.g., dry wit, dry subject).
In a literal sense, drögen describes something that is devoid of water or liquid. This could apply to the weather, describing a period without rain, or to a material, describing its texture and feel.
Figuratively, drögen can describe something that is uninteresting, dull, or lacking in emotion or excitement. A "drögen Witz" (dry joke) would be a joke delivered in a deadpan manner, perhaps even sarcastic or intellectual, rather than overtly humorous. A "drögen Vortrag" (dry lecture) would be one that is boring and uninspired.
The related word Trocken is often used interchangeably with drögen, but drögen often carries a stronger connotation of being boring or uninspiring in addition to the simple lack of moisture implied by Trocken. The intensity and nuances differ slightly between the two, and the precise choice of word depends on context.