cracker

a thin crisp wafer made of flour and water with or without leavening and shortening; unsweetened or semisweet

a poor White person in the southern United States

a programmer who cracks (gains unauthorized access to) computers, typically to do malicious things; "crackers are often mistakenly called hackers"

firework consisting of a small explosive charge and fuse in a heavy paper casing

a party favor consisting of a paper roll (usually containing candy or a small favor) that pops when pulled at both ends