If the definition of a black body is:
"A blackbody is an object that absorbs all of the radiation that it receives (that is, it does not reflect any light, nor does it allow any light to pass through it and out the other side). The energy that the blackbody absorbs heats it up, and then it will emit its own radiation."
Then why are light bulbs black bodies? Don't they generate heat themselves instead of absorbing radiation, then giving radiation out?