Answers/explanations:
Note: "F" is formal, "I" is informal, and the words in "()" are the words that explain why they are either formal/informal.
1.) Man, it stinks in here! - I
("Man" and "stinks" are used.)
2.) After work tonight I ate some grub and then chilled. - I
("Grub" and "chilled are informal.)
3.) Please refrain from interjecting yourself in my affairs - F
("Please refrain" "interjecting" and "affairs" are more formal.)
4.) Mind your own business, Dunk! - I
("Mind your own business" is usually used among colleagues, not in a formal setting.)
5.) The scent emanating from this room fails to please my olfactory sense. - F
("emanation" and "olfactory sense" are formal.)
6.) When Iarrived at my domicile this evening, I partook of sustenance and
enjoyed some quiet time alone. - F
("domicile" and "sustenance" are formal.)
Hope this helps! :D
