Farting in the office?

Pretty much every day I get to work and within an hour or so I need to drop my guts. I work opposite this right fat, slack, lazy, yawing whom I'm hoping everyone will think was the one what done the guffs as I don't want anyone thinking that the vile stench that permeates the office 3-4 times a day is me. I make a disgusted face 20 seconds or so just after I release my toxins and look in his direction, can anyone think of any other subtle ways I can hint that the stench of ronking **** is coming from him? Please don't suggest saying anything, I think that would make it more obvious that it was me, just subtle hints. Ideally I'd like him to get a written warning for this vile behaviour. If my marsh gas could be the catalyst for the eventual termination of his employment I would be a very happy bunny. Thanks in advance.