1. Do: A party, as in "We are having a leaving do for Sammy to wish him the best as he goes off to a new job."
2. Hen do/Hen party: Bachelorette party, as in "My hen do is in Louisville with all my closest friends."
3. Stag do/Stag party: Bachelor party, as in "He could not wait for his stag party in Vegas."
4. Mo: Moment, as in "I'll send the email to you in a mo."
5. Pudding: Dessert, as in "Our puddings tonight include chocolate cake, gelato, and macaroons."
6. Advert: Advertisement, as in "The company received a full page advert in the trade magazine."
7. Bespoke: Individualized, as in "Whole Foods specializes in bespoke cakes, which are made to order."
8. Cheeky: Ill-mannered in a rude way (but also can be in a comedic way), as in "His joke was a bit cheeky."
9. Bits: Part, action, or idea. See the first sentence at the start of this post {or should I say, bit? ;)}. The English use it a lot and I actually like it.
10. Knackered: Extremely exhausted, as in "I'm just knackered after this long day, and need to get to bed soon."