Brain teasers的意思是?

Brain teasers的意思是? Brain Teasers 7 Brain Teasers 6 Brain Teasers 1 Brain Teasers 8 Brain Teasers 3 Brain Teasers:Why do giraffes have long neck? Brain Teasers:Why do lions eat raw meat? Brain Teasers:When do people have two mouths? Brain teasers：Why is the pig always eating? Brain Teasers:What has everybody seen before but will never Brain Teasers:What has a mouth but never speaks?