Okay, this is now strange/weird. I bought some ads on Google AdWords. Fine works great. But after looking in my logs, I found out, that some referers are from ask.com. I checked, and really there is MY Google AdWords ad on ask.com as sponsored result.
No links or description from Google (Ads by Goooooogle). Even the link first goes to tm.ask.com.
Is this a partnership from Ask & Google? Or is someone tricking me with redirecting it from ask to ask ads, then google adsense to my site?

Ask has been partnering with google for ads for some time now, and the partnership witll continue into the foreseeable future.