First, stop saying,my oral english is poor, this is what foreigners hate to hear.
Second, treat them like your own friends, they're no different to us. Don't be that afraid, even if you say something wrong, just telling them and correcting your mistakes, they won't laugh at you. Relax, even themselves make mistakes when speaking English.
Third, pls not always ask them to talk to you just because you want to prove your oral speaking. Say, would you be comfortable if the foreigners ask you to speak Chinese because they want to improve their oral Chinese?