Trampolines are accidents waiting to happen. Just ask New York Yankee pitcher Joba Chamberlain who sustained a career-threatening ankle injury after playing on a trampoline with his son. Insurance companies won't cover injuries sustained by someone jumping on a trampoline. In fact, just having a trampoline on your property is reason enough for some companies not to insure you at all. Why? According to the Consumer Product Safety Commission, trampolines caused 92,159 injuries that required emergency room treatment in 2009 alone [source: Patel].