When a woman wears a pair of tight jeans that makes her flab spill out over the waistband, just like the top of a muffin sits over the edge of the paper case.
"Speak of the devil" is the short form of the idiom "Speak of the devil and he doth appear". It is used when an object of discussion unexpectedly becomes present during the conversation. For example, if Alice and Bob start discussing Charlie while he isn't in the room, and Charlie walks into the room, Alice or Bob might say, "Speak of the devil!"
出典:90210 Season 1, Episode 21: The Dionysian Debacle
カトリックスクールの女子校生たちがシルバーの噂をしていると、シルバーが現れたという文脈で出て来た表現です。
B@Z:I want to make my beer baby smaller and have a hourglass figure. :出てる下腹をへこませて砂時計のようなくびれが欲しい!! Plus, I want to have a thigh gap too!! : 太ももの隙間も欲しい!!