Contracting いる+の to

Grammar: Colloquial and Casual Speech » Contracting 〜いる+の to 〜いんの

In casual speech, いる followed by の may contract to いんの.

Examples

Is something there with いんの

Manga panel from 名探偵コナン showing example of Is something there with いんの.
名探偵コナン » Volume 9 » Page 11

In a game of hide-and-seek, Conan and Ayumu find they’re hiding on the same bench. Their conversation attracts the seeker, Genta, leading him to find Conan. As Ayumu sneaks away unseen, she signals an apology to Conan.

コナン:
「バカ 早(はや)く隠(かく)れてろ!」
“Stupid, hurry and hide!”
元太(げんた):
「ん? なんかいんのか?」
“Mm? Is something there?”

Where are you at with いんの

Manga panel from orange showing example of Where are you at with いんの.
orange » Volume 5 » Page 30

Azu is with her friends, waiting for Suwa. They call him to find what’s keeping him, and while Azu talks with Suwa by phone, she hears an echo of his voice in the distance.

あずさ:
「須和(すわ)? 今(いま)どこにいんの?」
“Suwa? Where is it you're at right now?”
須和(すわ):
「じゃあ もう切(き)る」
“Well, I'm hanging up now.”
あずさ:
「えっ」
“Eh?”

Why is it you're here with いんの

Manga panel from ひとりぼっちの○○生活 showing example of Why is it you're here with いんの.
ひとりぼっちの○○生活 » Volume 1 » Page 107

Aru returns to her classroom after club. Expecting the classroom to be empty, she’s singing a song about herself as she enters the room. There, she finds her friends idling away the time.

アル:
「なな 何(なん)で皆(みな)いんのよ!(誰(だれ)もいないと思(おも)ってた!)」
“Wh- why is it that you all are here?! (I was thinking no one was here!)”
なこ:
「(なんだ今(いま)の歌(うた)…)」
“(What was with that song just now...)”
ソトカ:
「師匠(ししょう)がアルを待(ま)つって」
“Master said she'd wait for you.”
アル:
「でも私(わたし)部活(ぶかつ)あるわよ」
“But I'm in a club!”