Just do street work--in an area where there is barely to no pedestrian traffic. Just half-heartedly hold the rags out, and just watch the cars speed by. You get to count the hour, but you place nothing. A variation would be to do a large bookstore--and browse the books instead of placing rubbish.
If even that bothers you, the Fake Time Slip works wonders. You do this by doing zero field circus for the month. At the end of the month, you make up something. Yes it's lying, but they lie all the time to get you into the cancer. And lying on your slip is better than lying at the door trying to get people to waste their lives on the cancer. You invent a number, usually around what you have been doing to slightly lower, and put that on your slip. You may also have to lie and make up a date--anything more than 3 hours, it's best to make up 2 separate dates on your slip. A fake rag placement will help--keep it about where you traditionally do, to a little less.
Warning: If you do the Fake Time Slip, try not to inflate the numbers too much. If you turn in slips of around 10 hours a month or more, and especially with several fake rag placements, the hounders are going to be pushing you to do even more. You will probably be given duties at the Kingdumb Hell, which you want to avoid at all costs. If your hours look good enough to them, you might even be recommended to be an assistant hounder. And, if your fake hours approach the 30s, you will probably be expected to auxiliary pious-sneer. It is much harder to do 50 fake hours than 2-3. Usually, 7 is the magic number--exceed that, and you are inviting "privileges(??)".