I was leafing through one of my hunting catalogues when I found something that made me laugh. "Look," I said to my wife, "what I've always wanted: A camouflage toilet seat."
"Get it," she said. "Then you'll have an excuse for when you miss."
"leafing through" の意味は文脈から、カタログをパラパラめくって見ている様子を想像できますが辞書で確認します。
・OneLook Quick Definitions: turn over pages ("Leaf through a book"); look through a book or other written material ("She leafed through the volume")
・Dictionary.com: to turn pages, esp. quickly (usually fol. by through): to leaf through a book.
ところで最後のオチがいま一つピンとこないのですが。 トイレで用を足していたので猟の獲物を見逃した言い訳に使えると言う事?