Ness' Luck stat in Earthbound.
Luck is a stat appearing only in Earthbound. Akin to IQ, its effects are not completely clear. It most likely affects the party's accuracy - chance to hit and dodge. Although it may seem that Luck would affect the chance to get a SMAAASH!! attack, it doesn't, as stated by the Friendly Mole between Twoson and the Happy Happy Village - the Guts stat does this.
The HP restored by Lucky Sandwiches is affected by the Luck stat.