A thoinkster is a dismissive name for a goofy female.
Thoinkster may also mean "hoe" or "thot" if used in the right context.
"Don't come for me, you thoinkster"
Straight Cheeks refers to the level of skill someone has at something which is inferior to most. You may also hear someone refer to such pisspoor skill-level as, "straight buns"
Yo, Mike is straight cheeks at 2K! He can't even guard with his defender!