To make someone's day: to make someone feels happy.

When someone makes you happy, you can say they make your day.

For examples:
Sam: Hey, Dara! what's you doin'? 
(សេម: អេ! ដារ៉ា, ឯងកំពុងធ្វើអ្វីហ្នឹង?)
Dara: I'm watchin' Charlie Chaplin's show. It's hilarious. He makes my day. 
(ដារ៉ា: ខ្ញុំកំពុងមើលការសម្ដែងរបស់ឆាលី ឈេបផ្លីន។ កំប្លែងណាស់ណា៎! គាត់ធ្វើឱ្យខ្ញុំមានអារម្មណ៍រីករាយណាស់។)

That's classic: that's very funny.

For examples:
When I was young, my grandpa always told me jokes. That's classic. Y'know?
(កាលខ្ញុំនៅក្មេងលោកតាខ្ញុំតែងនិទានរឿងកំប្លែងឱ្យខ្ញុំស្ដាប់។ វាពិតជាកំប្លែងណាស់។)

My hats off to you: this expression is used when you want to express your homage or admiration to someone.
(សូមគោរពសរសើរអ្នកដោយស្មោះ)
For examples:
1. My hats off to you, sir! You're such an impressive leader.
(សូមគោរពសរសើរលោកដោយស្មោះ។ លោកពិតជាថ្នាក់ដឹកនាំដ៏ប្រពៃមួយរូប។)
2. Sok is trying to help the impoverished people in his community. My hats off to him for his great job.
(សុខកំពុងព្យាយាមជួយជនក្រីក្រនៅក្នុងសហគមន៍របស់គាត់។ ខ្ញុំគោរពសរសើរគាត់ណាស់សម្រាប់ការងារដ៏បវរនេះ។)

To cushion the blow: to make it easier to deal with difficult situation or to make it less intensed. 
(សម្រាលស្ថានការណ៍ ឬ ភាពតានតឹងអ្វីមួយ)

*You can also say "to soften the blow" for the same idea.

For examples:
I understand that you're facing a really hard time during this pandemic. Therefore I wanna offer you with this small amount of money to cushion/soften the blow.
(ខ្ញុំដឹងថាអ្នកកំពុងជួបបញ្ហាដ៏លំបាកក្នុងគ្រាកើតមានជម្ងឺរាតត្បាតនេះ។ ដូច្នេះខ្ញុំសូមជូនថវិកាបន្តិចបន្តួចដើម្បីជួយសម្រួលស្ថានការណ៍ខ្លះ។)