Talk about feeling dumb! I thought you meant some kind of saltine cracker!! I grew up in the 50's and never heard of this gadget. We just put our SB eggs in egg cups and cracked the top with the back of a spoon, then picked off a little bit of the shell, then cut our toast in narrow strips and dunked right into the egg! Then when the yolk was gone, we dug out the whites with the spoon.
Soft boiled eggs are safe to eat as long as you use clean eggs with no cracks. The salmonella comes from the contaminated shell but cooking kills it. If the shell is even slightly cracked, the salmonella can get inside the egg and if you don't cook it thoroughly, then you can get sick. But an uncracked egg will have any contamination killed with the boiling water - same for poached eggs. So don't worry - enjoy your SB eggs!