Watch out for bare butts when traveling in Machu Picchu -- incidents of "naked tourism" at the 15th-century Inca citadel are on the rise, and getting under the skin of Peru officials.

According to the Peruvian Times, four American tourists were detained on March 14 for getting naked and posing for photos at the site.

In a pair of separate incidents earlier in the week, two Canadians and two Australians were detained for stripping down for pictures at Machu Picchu.

The bare-it-all episodes followed a 2013 incident in which a naked couple was videotaped by other tourists while streaking across Machu Picchu's grass field and bounding down a stone staircase like a pair of adolescent antelopes.

The website My Naked Trip features images of an Israeli man named Amichay Rab posing in the buff at sites around South America, including Machu Picchu.

Rab's long, curly hair and bold poses have won him a cluster of followers.

The photos and video have made the rounds on social media.

Peruvian officials are not amused.

Crackdown

Peru's Ministry of Culture has denounced the spectacle of nude visitors at Machu Picchu as "disrespectful" and "unfortunate events that threaten cultural heritage."

"There are places in the world that people can get naked, but not all places are (appropriate) for getting undressed," Alfredo Mormontoy Atayupanqui, director of archaeological resources for Peru's Ministry of Culture, tells CNN.

According to Mormontoy, park rules printed on the back of admission tickets warn visitors against being nude in public.

"Tourists should comply with local rules and regulations when they are traveling, otherwise there will be thousands of problems," he says.

Now, provide a numbered list of answers to these questions:

1. Where is this located?
2. What is that?
3. What is the concern here?
4. Who is upset about it?
5. What happened?
6. When?
7. How many?
8. For doing what?
9. Who reported this?
10. Was there anyone else?
11. Who was it?
12. What was the occurance?
13. Are any other ones mentioned?
14. Who was it?
15. What were they doing?
16. When was this?
17. What is being done about it?
18. Where?
19. About what?
20. Who voices their opinion on it?

Numbered answers:
1. Machu Picchu
2. A 15th-century Inca citadel
3. incidents of "naked tourism"
4. Peru officials are
5. American tourists were detained
6. March 14
7. four
8. getting naked and posing for photos at the site
9. the Peruvian Times
10. Yes
11. two Canadians and two Australians
12. stripping down for pictures
13. Yes
14. a couple
15. streaking across Machu Picchu's grass field
16. 2013
17. park rules warn visitors
18. on the back of admission tickets
19. being nude in public
20. Alfredo Mormontoy Atayupanqui