How To Avoid Being Scammed And Bullshat "at", sounds more professional.
Discussion
I don’t think so because you say “you’re bullshitting me” not “you’re bullshitting at me”, implying it’s a transitive verb with the target of the bullshit as the object of the clause. then you just have to conjugate as a past participle and “bullshat” is both funny and arguably correct given “shit/shat”.