Thomas Cuthbert laughed, "if I was 20 years younger" as he shook 49-year-old Melania's hand - right in front of President Trump, 72.
Trump added: "It's my honor, believe me, thank you very much."
Speaking after the meet-and-greet, Mr. Cuthbert, from Elmstead Market, Essex, said that Trump "came across very well".
He added: "He surprised me, when you see someone on the TV but he seemed different, he seemed one of the boys.
"His wife was very pleasant as well."
The joke came at the end of an hour-long D-Day ceremony to remember the historic moment hundreds of thousands of troops stormed the beaches in World War Two.
President Trump performed a reading at the ceremony, which also featured a series of poems, dramatizations, songs and speeches.
This article originally appeared in The Sun. For more from The Sun, click here.