Why can't I have nice dreams?

I had a dream that I was staying somewhere near the middle of America, or some other place where you would normally expect to find absolutely vicious small creatures (like Australia somewhere). The owner of the house opened the fridge, took out a tub of Land-O-Lakes spreadable, opened it and said "Oh, it looks like we've got butter-lions".

He pointed down to a black speck visible through a small hole in the surface of the butter, and scraped it gradually away to reveal a monstrous prawn-like insect, long, dark and segmented. Apparently, they sometimes got into tubs of butter and hid there inert until they were woken up by someone opening the lid - holding the first one, he scraped down further and pulled another one out.

I was particularly unimpressed when somebody tried to demonstrate they weren't harmful by putting one down the back of my shirt.

Why can't I dream of something nice? But then, when my real life this week has involved sitting in a car with a gryphon in the passenger seat, waiting at the lights for a purple dog playing the saxophone to walk across the road, weird dreams hardly seem necessary.