dunker

noun

1. Someone who dunks.
2. A person tasked with performing or training others in slam dunks.
3. A biscuit that is suitable for dunking in a cup of tea.
4. Any snack food suitable for dunking in sauce.
5. A kind of sonobuoy.

   “Active sonar, for aircraft purposes still largely associated with dunking, suffers less variability but often has less range. […] Development of both dunkers and sonobuoys continues towards lower frequencies, implying bigger arrays, and deeper deployments.”

   “Then they drop the dunker into the water and spin it around a few times so you end up upside-down.”