The pictures I use on the CleanLaugh site are, for the most part, floating around on the net, source unknown. For that reason, I can neither give nor deny permission to use them. That decision is up to you.
However, in some cases I have known the owner of a photo and received their permission to use it. In these instances you will see a copyright notice on the photo itself and either their e-mail address on the photo or a link to their web site near it. Please contact the owner directly to get permission to use the picture (and please do mention you saw it on the CleanLaugh site).