Do somebody a/no service Definition 1 of 2Pro Tip 1/3Positive Impact Use this phrase to highlight a helpful action with positive effects on someone. Tutoring the new student did him a great service. Pro Tip 2/3Gratitude Expression This phrase is often used to express thankfulness for someone's assistance. You really did me a service by proofreading my essay. Pro Tip 3/3Formal Acknowledgment It's often used in formal contexts to acknowledge someone's contribution or help. The community did her a service by supporting her initiative.