chat someone up—(UK coll., of men) try to make friends with a woman by talking to her:
- I did my clumsy best to chat her up and talked to her about my interest in archaeology.
talk someone up—(chiefly U.S.) praise smb.; speak in support of a person:
- The coaches have been talking him up since early in the preseason.
Note: The expression is not antonymous in meaning to the phrase talk someone down—
1. silence smb. by speaking more loudly or aggressively; win out over a person in an argument, etc.:
- Eventually, however, Mr. Brown talked down all the other members of the committee.
2. convince a person to lower the price:
- This is my final offer…. Now, don’t try to talk me down.
3. provide a pilot with directions by radio which enable him to land:
- They get us on the radar screen and talk us down on to the runway.
See also: talk down to someone / talk up to someone.