expression, godan verb (-ru)
act like equals; put on airs of equality
Colloquial phrase used when someone behaves as if they are on equal footing with another person, often with a nuance of showing off or asserting equality in a presumptuous way. タメ comes from ため (equal, same rank).
See also: ため
後輩のくせにタメを張って話す。
He talks to me as if we were equals, even though he's my junior.
あの新人はすぐに上司にタメを張ろうとする。
That new employee immediately tries to act like he's on the same level as the boss.