According to the actions of President Bush, a fourth grader is someone who can replace Bush if he successfully gets assassinated by a pretzel.
Although this definition gives too much credit to Bush, it will suffice.
Also see 4th grader
4th grade Teacher: Okay, class what comes after W?
fourth grader: X?
4th grade teacher: Correct Billy.
George W. Bush: X is for oil!
4th grade teacher: -silence-
A fourth graderflame thrower is when a lighter and aerosol can are used to make a large flame. It is called a fourth grader flame thrower by some because those are materials kids can easily get access to in their houses. Because they are still adolescents, they are find it amusing to burn other objects using these home made flame throwers. Despite the name, it is still enjoyable for many older people, typically men.