Billy: Uh...that's Greek to me.
Jennifer: That means they have tapered legs.
Billy: Well, mine are baggy. They're the kind of pants you can lounge around in.
Jennifer: Mine are, too.
Billy: So maybe we shouldn't go out after all.
Jennifer: Yeah. Let's just lounge around!

That's Greek to me. 　
Greek是「希腊文」，十分冷僻难学，所以这句话的意思是「我不懂，我无法理解。」

tapered legs 　
裤脚收窄的剪裁

lounge around 　
（在室内）闲晃
A: How do you spend your week off?
你休假的礼拜都怎么过？
B: I just lounge around the house.
我就待在家里闲晃。

比 利：呃……我鸭子听雷。
珍妮花：那是指这是AB裤。
比 利：我的是宽松剪裁。这是那种穿来在家里东晃西晃的裤子。
珍妮花：我的也可以啊。
比 利：其实我们或许根本用不着出去。
珍妮花：对啊。我们待在家里晃就好了。