Nested Loops Question___>

This code should work:

persons = ["John", "Marissa", "Pete", "Dayton"]

them = ["Dayton", "Pete", "Marissa", "John"]

for x in persons:
    for y in them:
        if not x==y:
            print(x, "Meets", y)

You can also use combinations() from itertools (docs). This will have each person meeting everyone else exactly once, so you'd have John meets Marissa or Marissa meets John but not both.

from itertools import combinations

persons = ["John", "Marissa", "Pete", "Dayton"]

for person1, person2 in combinations(persons, 2):
    print(person1, "Meets", person2)

Output:

John Meets Marissa
John Meets Pete
John Meets Dayton
Marissa Meets Pete
Marissa Meets Dayton
Pete Meets Dayton

In addition to @itsanantk answer, when you want to eliminate same pairs (i.e. treat "John Meets Marissa" and "Marissa Meets John" as a same), you could use following pattern:

persons = ["John", "Marissa", "Pete", "Dayton"]
for i, x in enumerate(persons):
    for y in persons[i+1:]:
        print(x, "Meets", y)

Here, every person meets every person standing after it in the list.

Same effect could be achieved using more concise syntaxes of itertools module:

from itertools import combinations
persons = ["John", "Marissa", "Pete", "Dayton"]
for x, y in combinations(persons,2):
    print(x, "Meets", y)

This code should also work:

persons = ["John", "Marissa", "Pete", "Dayton"]
them = ["Dayton", "Pete", "Marissa", "John"]

for x in range(len(persons)):
    for y in range(len(them)):
        if x != y:
           print(f'{persons[x]} meets {them[y]}')

Output:

John meets Pete

John meets Marissa

Marissa meets Dayton

Marissa meets John

Pete meets Dayton

Pete meets John

Dayton meets Pete

Dayton meets Marissa