This is a hard one to say in a simple word, so first I will ask you the following. Do you remember those games you played in the elementary school cafeteria?
`If you were stuck on an island with one person, who would it be? The bride of Chucky or the kid who eats his boogers in class 2B?`
`If you had to choose how to die, would you die by having a bear eat your face, or by being lowered into a tank full of fire ants?`
If you were a Japanese kid, you might call these questions マシ (mashi). Basically, you use it when you are forced to make a choice by comparing things, usually distasteful things. So, if the kid across from you tells you he dares you to lick his shoe, and you wanted to say `I`d rather die`, you might say 「死んだほうがマシ・しんだほうがまし」.
If someone uses `mashi` to ask a question, it seems to imply something like `All of the alternatives are bad, but which is comparatively least bad?` If you use it to answer a question, you`re implying something like `Well, both of those suck, but if I really have to choose I guess the least suck-tastic is this option.` There kanji for it is 増し, but I always saw it in katakana as マシ.
I came across this word several times while reading the Japanese translation of the Korean novel 'The First Shop of Coffee Prince." Some people might recognize the name, since it was dramatized for television and is pretty popular still. It reads like a manga (the protagonist is mistaken for a boy/masquerades as one, and when a guy develops feelings for her, thinking she`s a guy, he thinks he`s gay, and of course all of this mistaken identity/identity crisis craziness begets quite a few laughs), so if you want to try reading something for entertainment value so you don`t feel bad when you can`t read half the kanji contained in the sentence, I`d recommend it. Maybe I`ll translate some bits as practice.