在英语中，请客吃饭可以用以下几种表达：

1. "It's my treat."

意思：这顿我请。

例句：Let's go eat. It's my treat.

2. "This is my round."

意思：轮到我了。

例句：Let's dine out this evening. This is my round.

3. "It's on me."

意思：这顿算我头上。

例句：Let's grab some Chinese food. It's on me.

4. "I'm paying for everything."

意思：我支付所有费用。

例句：Tonight's dinner is special, I'm paying for everything.

5. "Dinner's on me."

意思：晚餐我请客。

例句：Let's go to the restaurant. Dinner's on me.

这些表达方式根据不同的场合和语境可以选择使用，以确保礼貌和得体