To get tongue-tied, flustered, or lose your train of thought while speaking. It refers to getting stuck in the middle of a sentence and not knowing how to get out of it. (The term comes from batata, the word for sweet potato, implying a state of being stuck or slow-witted).
I do not know what I was saying to you... I got abataté.
Slang that originated in the Rio de la Plata region at the end of the 19th and beginning of the 20th centuries. It is generally associated with tango lyrics (the Rio de la Plata is the estuary area including Buenos Aires and Montevideo).
Argentines speak in Lunfardo without even realizing it.