I think I read somewhere that she said that she was specifically referring to Derrick's impersonation (during which he prayed) of her in the ill-advised TAFY play.
As far as what some have been seeing as Donny's "mean streak," sure he came up with some zingers (I saw the shows, feeds and updates), but IMHO it was nothing harsher than what I'd expect from an adult with a quick wit and a somewhat subversive sense of humor. When I worked in a male dominated industry, those kinds of back and forth jabs were appreciated and even affectionate; I knew I was accepted when I was included in the teasing. Heck, even holiday dinners in my family can be (affectionately) rougher than what he doled out.