import pygame
import random

pygame.init()
w  = 500
h = 500
screen = pygame.display.set_mode([w,h])

running = True

x = 200
y = 200

screen.fill((255,255,255))

while running:
    for event in pygame.event.get():

        if event.type == pygame.QUIT:
            running = False

    x = random.randint(0,500)
    y = random.randint(0,500)
    color = (random.randint(0,255),random.randint(0,255),random.randint(0,255))
    pygame.draw.rect(screen, color, (x,y, 50,50))

    pygame.display.update()

pygame.quit()