The phrase "to dish out" means to give or provide something, often in a critical or negative manner. In this context, it seems that the speaker is suggesting that they will say something unpleasant about another person.
Sentences with «dish someone use»
The size and number of dishes used in a bird cage will depend on the size and number of birds being kept, as well as the species. (petbusiness.com)
A very interesting baked dish using pasta and pumpkin which makes it very healthy as well. (bembu.com)
The amazing hotel chef creates a variety of creative dishes using fresh quality local products for breakfast, lunch and the evening meal. (loveholidays.com)