How do you get LLMs to stop spewing corpo speak?

Whenever I use an LLM chat bot for anything it always answers with this fake positive corp tone that we all know. And I absolutely hate that. I cannot stand corpo speak and the LLM style makes want to puke. To cut the rant short: How exactly do you stop it from doing this? I do not just mean the style of the response but also the response pattern: making assumptions instead of asking questions, always agreeing with me, having this fake differentiated view on everything, telling me it understood something and then doing the exact opposite.

I know I cannot make LLMs more intelligent by prompting, they will always hallucinate and get some things wrong, but I want to at least get it to be less of an asshole about it.

So, what do you do? I followed some generic advice like using positive instructions instead of negations, using examples, but I cannot get the corpo slop tone out of it.

General advice is welcome, but I'm mostly looking for specific verbatim examples of system prompts that you use.