Pain in the neck: Someone or something that irritates you. "Oh no, your mother's not coming to visit again, is she? Last time she was here all she did was tell me I should get a better job and buy a bigger house for us and ask why we hadn't given her any grandchildren yet. She's such a pain in the neck!"
Funnily enough: Something that is unusual or ironic. Gene Simmons of the band KISS spits blood on stage as part of their act, but, funnily enough, whenever he has a steak in a restaurant he orders it "well done" or "burned." He can't stand the sight of blood or red meat on his plate.
Out and back: Sorry, I'm unfamiliar with this idiom. Can you provide an example of it in a sentence?
Get stuck: End up with, not by choice. "I went to lunch with Fred, Brian and Roger yesterday, but since all three of them had 'forgotten' their wallets, I got stuck with the bill."
"I was late in registering for classes, and most of them were filled, so I got stuck with Introduction to Forestry and Ancient Etruscan Literature."
Student or Learner