Garageband built in keyboard samples

yes. it is.
make a new software instrument and then make it a sound effect file. from there go into the musical typing thing. Then you can drag in sounds. and play them with your keyboard. This does however get rid of your sound effects for that file. so if you used the comedy sounds, to input something else, you wont be able to acces them throughout that file. IT wont delete them of garageband tho.

 

You can keep the ones that are there...

Simple open comedy noise, then in the edit part where the effects are, there should be Instrument generator : and under that should be Sound Effects > Comedy noises.

Click on the pencil at the right. Essentially, edit the instrument. In this new window, click on comedy noises in the pop up selection menu click make preset. It'll essentially make a copy of comedy noises so you can put what ever samples you want in it without loosing comedy noises.