Cactus Study

At Christmas, I discovered a cactus at my neighbors house. It had it's own version of Christmas ornaments. I'd never seen anything like it. I grabbed some photos. I love the last one best. Looks like the dude is laughing. The white things are really cactus seeds. Too funny! I googled this to try and find the name of this cactus but to no avail. re there any I-people who know what it is?