def combination_of_two_lists(lst1, lst2):
    """
        ["f", "m"] and ["wb", "go", "re"] => ["f_wb", "f_go", "f_re", "m_wb", "m_go", "m_re"]
    """
    return [e1 + "_" + e2 for e1 in lst1 for e2 in lst2]