When Lauren snaps and kicks open the door to where the drug dealers are, holding them and gunpoint (with a fake gun) and roaring at them as a crazy cop—"New Yawk" accent and all. Sandy quickly gets into it, too, and their performance is at once hilarious and Badass—making the guys break quickly enough.
Sandy: You'd better tell her the name—she's kinda cranky...!
When Lauren and Sandy are at the airport, trying to find out the flight Michael is leaving on. It's technically illegal for the people at the desk to give out such information. Bribery is also out. Cue Lauren tying her white neckerchief around her head, and then approaching the desk with a Czech accent, giving a very sweet and touching Tear Jerker of a story about the girls being refugees from Czechoslovakia who are awaiting a reunion with their father who has finally escaped, himself. Keep in mind that Lauren is improvising off the top of her head—and nonetheless makes the yarn sound very believable. (In fact, though the clerk ultimately doesn't buy it, she does give them the info precisely because she admires Lauren's cleverness in concocting the tale.)
Sandy also manages to keep up well with Lauren's improvisation—amid the limitations Lauren (understandably) imposes on her by stating early on that "my sister" cannot speak a word of English....
Lauren:("Explaining" to Sandy in Czech-sounding gibberish, except for—) —Papa!
Sandy:(Tearful mutter—Czech accent) ...Papa...?
(They hug each other tightly, sobbing)
A more subtle example, but highly significant nonetheless, is when Lauren manages to, for all intents and purposes, sweet-talk a CIA operative into telling her and Sandy classified information about Michael. Granted, she does point out that she saved the agent's life, but still!
(With a warm smile and amused tone) "You're not authorized to de-brief me...?"
At the film's climax, Michael chases Lauren across the mesas in Las Cruces. She runs for her life, trying to shake him by leaping from one dangerously high and narrow mesa to the next. The final one requires a massive jump, which she accomplishes with an incredible grand jÚtÚ. Michael is not so gifted—he attempts the jump but doesn't make it. As he falls, screaming, to his death, Lauren leans over the edge of the mesa and gleefully yells, "Nine years of ballet, asshole!"