I know how NOT to use a P-38...
1) They are not good fuse replacements
2) They are no substitute for a bladed implement
3) Should never ever be used to clean under fingernails
4) Should never be worn alongside dogtags, even when covered with heat shrink; I have an interesting scar.
5) They are not a miniature prybar
All that being said, they WILL open a can. Never got it down to 38 motions, and a regular manual can opener is more efficient. I do carry one in my EDC, but will reach for can opener blade of SAK first (too many bad memories