lay possum / play possum

狸寝入りをすると言うのは日本語特有な表現と思っていましたが、The Quiet Americanに同じ様な表現が次の様に出てきました。
Under my breath I said, 'Go away, Pyle. Don't come near me. I don't want to be saved.'
'Thomas.' He was hitting at my door, but I lay possum as though I were back in the rice-field and he was an enemy.
辞書にこの表現の説明があるか調べましたが見当たりません。しかし "play possum" と言う表現が一般的に使われることが分かりました。
・Wikitionary: play possum: 1. to feign death; to remain quiet and still to escape attention or remain undetected; to lay low. 2. to feign sleep, illness, etc. When we used to get home late at night, I would play possum so my daddy would carry me inside and put me in bed.
・Wikipedia: Playing possum: Apparent death, colloquially known as playing dead or playing possum, is a behavior in which an animal takes on the appearance of being dead. This form of animal deception is an adaptive behavior also known as tonic immobility or thanatosis. Apparent death can be used as a defense mechanism or as a form of aggressive mimicry, and occurs in a wide range of animals.
"tonic immobility"と "thanatosis" は覚えにくいですね。Wikipediaには "Apparent death" の項目で狸以外にも色々な動物が "Playing possum" をする説明が写真入りで掲載されています。