something_dict = {
    'a': [1, 2, 3],
    'b': [4, 5, 6],
    'c': [7, 8, 9],
}

# 1. Initial
something = sum([zip((k,) * len(v), v) for k, v in something_dict.iteritems()], [])

print something

# 2. Explicit variant
def flatten_dict(d):
    for k, values in d.iteritems():
        for v in values:
            yield k, v

print list(flatten_dict(something_dict))

# 3. Itertools variant
from itertools import product, chain

print list(chain.from_iterable(product(k, v) for k, v in something_dict.iteritems()))