There's a good article about fart gas composition on Chemistry World (you can google it yourself so I don't get banned for posting a link). Anyways, turns out around a third of us DO produce methane. So yes, some of us are indeed cows. Also, our farts often contain tiny amounts of hydrogen sulfIDE (H2S) but not H2SO4, unless you're making some seriously questionable dietary choices.

Fun facts about H2S:

• you can smell it at <1ppm
• above 20 ppm can cause airway irritation and shortness of breath
• above 100 ppm is considered immediately dangerous to life and health
• around 150 ppm you actually stop smelling it after a while. Your sensory system gets so fatigued by the constant stimulation it just peaces out.