It was interesting to me. I was using sp_HelpText to see the text of the stored procedure. Stored Procedure were different so I had copied sp_HelpText on my clipboard and was pasting it in Query Editor of Management Studio. In rush I typed twice sp_HelpText and hit F5.
Result was interesting. What are your guesses? My team mates and few of my readers suggested : SQL Server will be in recursive loop, SQL Server will be not responde, SQL Server will throw an error.
Result was as expected. SQL Server did its job and displayed the text of sp_HelpText. Nothing unusual happened. This reminded me question I was asked in my high school exam : Write C program, which will print itself. sp_HelpText twice does the same thing. It prints itself.
Reference : Pinal Dave (http://blog.SQLAuthority.com)