Casual — to friend
In-flight
ブランケット、貸してくれない? — Could I borrow a blanket? (In-flight, Casual — to friend, JLPT N4)
You
ブランケット、貸してくれない?
ぶらんけっと、かしてくれない?
Could I borrow a blanket?
Romaji: Buranketto, kashite kurenai? / Reply Romaji: Mochiron, hai dozo. Samui yone?
Reply
もちろん、はいどうぞ。寒いよね?
もちろん、はいどうぞ。さむいよね?
Sure, here you go. You're feeling cold, right?
Gesture & etiquette
Smile and hand over the blanket, perhaps pointing to the overhead compartment or seat pocket if necessary.
Do not use formal 'Desu/Masu' endings as the relationship is casual. Avoid shouting on the plane.