To say someone (usually female) has bad grades is a euphemism for saying they have large breasts. For instance, a girl with D's (really bad grades) has really big breasts. You can say the worse the grades someone has, the bigger their breasts.
Did you see the new girls in English class, she had really bad grades!
A Shackteau is a humble, weather-beaten, structurally questionable shelter located in a spectacular or highly coveted place—Wales, Jackson Hole, Sun Valley, Crested Butte, coastal Maine, the Alps—where the building itself may be worth almost nothing, but the dirt, view, access, and mythology make it absurdly valuable.
In use:
Shackteâu - We thought it was an abandoned shed until the realtor called it a rare alpine Shackteâu with unobstructed views and listed it for $2million.