just flash me
Since English is so widely spoken, and all education is done in English, Kenyans have their very own pronunciation, word usage, and idioms, which they teach kids in school, including silent Rs. That won't confuse you much when you're speaking English with a Kenyan because you will consider it simply part of the accent. What might confuse you (and has confused me) is odd word usage. Some of it is British, and I will try to leave those out.
Iron box - I think of an actual box made of iron, where maybe you store important things. Maybe it's fireproof. No. This is an iron for clothes.
Tissue paper - It's not thin sheets for wrapping breakables or stuffing in a gift bag. It's toilet paper.
Overspeeding - This is kind of self-explanatory, just redundant. It means speeding.
Flu - It could be flu, or cold, or allergies, or anything involving a runny nose. In a similar vein, any illness that includes coughing is asthma. And speaking of vein, in Swahili, the word vein is used for many different types of body parts, and it may be translated into English that way. It's difficult to find out exactly what is ailing a person.
Sweet - They use the noun sweet for candy, as in "Would you like a sweet?" That's normal, British English. The one that's specific to Kenya is the adjective. Kenyans are so obsessed with sugar, their only word to describe something that tastes good is sweet. It doesn't matter if it is savory, spicy, tart, or bitter. If it tastes good in Kenya, it's sweet. Furthermore, there is no such thing as "too sweet."
Flash - Don't be alarmed if a Kenyan threatens to flash you (or if they ask you to flash them)! It means to call someone and hang up on the first ring because you have no credit on your (prepaid) phone, and you hope they do and will call you back.
Hotel - It took me ages to figure this one out. Yes, it could be a hotel, but it is probably just a diner.Paper bag - In the US, paper and plastic are opposite types of bags, one made of brown paper, the other of thin plastic. In Kenya, paper bag means plastic bag. "Paper or plastic?" "Are those different things?"
Me I - Here's another self-explanatory one, but very common in Kenyan English. Just to emphasize that I'm talking about myself, I will say "Me I" instead of just "I." It's so popular, you can even get a "Me I" shirt (but the one pictured is sold out right now).