I have two dataframes df1 and df2 and I want to create a new column in df1 and set values in that column to 0 where rows in df1 are contained in df2. More specifically:

```
sample_data_1 = {'col1': ['80', '8080'], 'col2': ['0.0.0.0', '143.21.7.165']}
df1 = pd.DataFrame(data=sample_data_1)

sample_data_2 = {'col1': ['80', '8080', '1', '8888'], 'col2': ['0.0.0.0', '143.21.7.165', '1', '5.5.5.5'], 'col3': ['1','2','3']}
df2 = pd.DataFrame(data=sample_data_2)

     col1          col2
0    80         0.0.0.0
1  8080    143.21.7.165

   col1          col2 col3
0    80       0.0.0.0    1
1  8080  143.21.7.165    2
2     1             1    3
3  8888       5.5.5.5    4

```

I would like to add a column to df1 and set those values to 0 where col1 and col2 in df1 match col1 and col2 in df2. The resultant dataframe should look like:

```
    col1          col2    score
0    80         0.0.0.0   0
1  8080    143.21.7.165   0

```

When the dataframe sizes are the same, I can do a straight comparison using .loc function and logical and's, but when they have different shapes I get "unable to compare series" exceptions. Thoughts? 

Thanks for the help!