Is it right to say "I was talking to a 49er" to aim that "I was talking to a 49-year-old man"?
I know that it's meaningless to say it, but my question is:
"Is (age)er = (age)-year-old man"?
No. Referring to a forty-nine-year-old man as a "49er" is not idiomatic in either American or British usage. The more idiomatic expression would be "49-year-old," as in:
I was talking to a 49-year-old.
"49er" or "forty-niner" is an English word, but it has nothing to do with age. It refers to one of a wave of gold prospectors who traveled to the American West, and especially California, in 1849. So, for example, the first verse of the song "Clementine" is:
In a cavern, in a canyon,
Excavating for a mine,
Lived a miner forty-niner
And his daughter, Clementine.
This is why San Francisco, California's American football team is named the "Forty-Niners."
DJ Jazzy Jeff and the Fresh Prince referred to a gold-digger as "The girl ain't nothing but a 49er" in their track "You Got It (Donut)" from their 1989 album And In This Corner...
I was contemplatin' her bein' my wife and All she was tryin to do was siphon Every single dime that she could extort She was Jane the Ripper, and she couldn't be caught My friends tried to tell me but I stood behind her ("The girl ain't nothin but a 49er") They tried to tell me but I couldn't be told Because her beauty was a shovel that was diggin for gold
A "gold-digger" is a person who dates others purely to extract money from them, in particular a woman who strives to marry a wealthy man, so you could use "49er" as a slang reference to this type of person. Probably not very common usage judging by having to use a 25 year old reference ;)
No, a 49er refers to a person who plays for the San Francisco 49ers, the American Football team.
You: "I was siting next to a 49er at the bar today."
Friend: "Sweet! Was it Frank Gore!?!?"
As others have said, the correct way would be to refer to him as a "49-year-old".
"Thirty-something" originally meant a person who was forty one, "in denial" about their age, and still pretending they were in their thirties.
Now, it just means someone who is actually in their thirties.
But "forty-niners" is, as the person above said, a reference to the California gold-rush boom in 1849.