I don't think one needs to be paranoid about posting jokes online- CBSA and the IRCC officers are not just sitting there waiting to screw you over ridiculous things. However, if you have publicly posted pictured of yourself somewhere else in the world when you were claiming to have physical presence in Canada at the same time, that might make them dig deeper and ask for further proof that you were in Canada.
If you post online that you were in some sort of altercation with someone, or the law, or whatever, and that information was made public by you, but you didn't disclose that in your application, then they may take a closer look. If you gave employment history in your application, then your Linkedin says something completely different (different countries, different employers, different length of employment), then they may want to investigate, reach out to the employers listed in the application, ask you for letters from the employers or whatever.
They will not be like "well he's is a Trump supporter, there's not way im approving their TRV". We have to trust the process.