It's true that you can 'fake' praying in tongues, just like you can fake being slain in the Spirit. But I know if anyone told me I was faking I'd jump down their throat (which is not a good thing I know).
The speaking of tongues at the Pentecost is different to praying in tongues, which Paul says (in 1 Corinthians 14) is impossible to understand, without someone who can interpret it. For me praying in tongues is a private prayer language, that I use during worship, not something I do to show off. When praying with other people it is often better to pray in your 'normal' language.
He's charging into hell and bringing heaven with him!- Rob Bell
"So you are no longer a slave, but a son; and since you are a son, God has made you also an heir" - Paul - Galations 4:7