Final answer:
In the movie 'Selena', Marissa is portrayed as Selena's best friend who makes fun of her Irish dancing.
Step-by-step explanation:
Selena's best friend who made fun of the Irish dancing was named Marissa. In the movie 'Selena' based on the life of Selena Quintanilla, Marissa is portrayed as someone who teases Selena for participating in Irish dancing. Marissa's insensitive comments show a lack of understanding and acceptance of different cultures and demonstrates the importance of respect and inclusivity.