Yes, it is "Heiße Bengel", and if you don't have an ß, you can write "Heisse Bengel" instead. Otherwiese, we use ß after a long vowel or a diphtong, and ss after a short vowel. Before the orthography reform, it was even more complicated... But I think, we should keep the ß. It is cultural heritage, like the movie above. :D
