Several short ones

From Robert Tomik
Agent: "How many times have you been arrested by La Migra"
Alien: "You mean here in Del Rio?"
Agent: "No, I mean anywhere along the border"
Alien: "I've never been arrested by La Migra"
From Arnulfo Cortes
A fellow agent from Puerto Rico, asked a lady at a checkpoint “Cuantas veces ha sido cojida por la migra?“ Her answer was “Cojida muchas veces, por la migra nunca.”

From Jose A. Flores
I was working a DL Check at a checkpoint when I was THP Trooper. It was nighttime and a cattle truck pulls up for inspection. The PA goes to the back and shines his flashlight into the cattle carrier, and we hear a loud MOOOOOOO!! Except it wasn't a cow, it was one of 20 illegals being smuggled! I begged the PA to let the alien go on principle, but he wouldn't budge.  Who knew a couple years later I would join the USBP? (Mean Green 205)!
From Ron Kidd
During I-213 interview practice with aliens pulled from the Los Fresnos holding area a trainee agent was overheard asking,  “¿Cuántas pulgadas tienes?”  The alien looked puzzled.  Our trainee was attempting to ask how tall the alien was, but of course was getting things jumbled.  Several times he repeated,” ¿Cuántas pulgadas tienes?”.  By this time, us other trainees were starting to snicker but the room broke up when the alien compliantly held up his hands about six inches apart.