To be back on one's bullshit is to regress to a former state of being, often a rather unhealthy and
self-destructive state. It implies falling back into one's old ways and habits after a brief period of "self-reinvention".
Being back on one's bullshit is not
necessarily a bad thing per se. Perhaps that person had come to terms with their quirks, absurdities, and insatiable/irrational desires. No longer do they try to repress those self-destructing behaviours and compulsions in hopes of becoming better, because they know that one day they will
eventually give in; they can run but they can't hide from their true sordid selves. In other words, they continue to seek self-improvement and strive towards self-mastery, but they don't try to repress their former bullshit. Besides, that bullshit defines you and who you are and you can't feel like "you" without it.
Jennie: Jimmy wth??
What's up with those
cross-dressing pics you sent me last night, I thought you had already broken out of that paraphilia of yours
Jimmy: Well
what can I say, I'm back on my bullshit, and I don't intend on hiding it anymore.