I have trouble understanding 叫んどんねん in this panel. I thought it must be 叫んでおらない but I don't think it makes sense in this context.
The talker is saying "トイレの個室で何叫んでるんだよ" (Roughly means What the hell are you yelling about in the bathroom stall?) in Kansai dialect, not slur.
It can be divided like:
- トイレ | の | 個室 | で | 何 | 叫んどん | ねん
- トイレ | の | 個室 | で | 何 | 叫んでるん | だよ
叫んどんねん is short for 叫んどるねん, which is short for 叫んでおるねん, which is 叫んでいるんだ(よ) said in Osaka-ben. There is no negation.
- おる is used instead of いる in many western dialects to denote progressive aspect. See: おる in honorific contexts and Existence verbs in the Kansai Dialect
- ておる/でおる very commonly contracts to とる/どる. See this chart.
/r/ + vowelbefore
/n/can contract to ん (also in Tokyo colloquial speech). See: Why is the て-form being used before ん？
ねん is a Osaka-ben specific sentence-final particle which can replace んだ(よ)/のだ(よ).