From a quick search, a few sources claim 0.5 - 1 gram of table salt per 1 kg of body weight. 25 grams or 4 tablespoons of table salt could be lethal. I've seen higher amounts also.
Can cause confusion, muscle twitching, coma and seizures. Potential death, no guarantee.
Can't help but think that it would taste nasty as hell and would result in puking before any damage happened.