Well I don't smack it with a lot of force. I just lay the smack pack on the counter feel for the inner packet move it to the corner and push down on it with the palm of my hand. It pops fairly easy this way.
I usually push the nutrient packet into a bottom corner and secure it there with my left hand, and then give it a smack with the right. It pops easily that way. No need to spank it with the old BDSM paddle.
I pushed the little guy into one corner, and smacked the pack holding it in my left palm with my right hand. I am hoping it actually popped when that happened and it didn't have a small leak before hand. Today the batch still isn't taking off, although I dumped the pack into a sanitized container and it was bubbling away when I tossed her in.