Wrong. Attach red to + of dead battery first. Then attach the other red to + of good battery. Third, attach the black to the - terminal of the good battery. You should attach the last black to the engine block of the vehicle with the DEAD battery LAST. Remember "the last thing you do with the dead is put them in the ground" (unless you're into some freaky stuff).
Thank you for the correction.
The whole point is that batteries can (or used to be able to) produce an explosive gas.
Make the final hook-up away from the batteries themselves. If there is a spark, it won't ignite the battery gases (if there are any).
Sealed batteries MAY not have this issue.... I dunno.
I beat Selma to the punch, TWICE!