This is the most direct translation of the phrase "你在跟我开玩笑吗" in English. However, depending on the context and tone, there are several other ways to express this sentiment. For instance:

- "Are you serious?"

- "Come on, really?"

- "You can't be serious."

- "No way!"

Each of these alternatives carries slightly different nuances, so choosing the right one depends on the situation. For example, if someone tells you something unbelievable, like winning the lottery, you might say "Are you serious?" with a mix of surprise and curiosity.

If you're looking for a more casual or conversational tone, phrases like "You’ve got to be kidding!" or "No, seriously?" could also work well. The key is understanding the emotional undercurrent—whether it's disbelief, humor, or genuine shock—that guides which expression feels most natural in any given moment.