It depends on the context of the situation. I'm more likely to keep silent though. There are others ways to show who Jesus is in us without talking about Him. Show Grace, Forgiveness, Mercy, Compassion, Community, Letting others have the spotlight over ourselves...and even going out of our way to encourage that. Don't participate in gossip instead, shut it down. Don't laugh at inappropriate so-called humor, simply excuse yourself. Volunteer when possible. Be on time. Show generosity. Encourage others. Doing these things will raise eyebrows. Don't keep your faith a secret if someone asks you a direct question, but don't broadcast it either. Always Always pray over the work space and for those who are in leadership. Be humble. There's that old saying 'Actions speak louder than words'.
Of course the gospel is shared verbally, but who even wants to hear from us if our lives don't align with what we're saying?
What other practical suggestions can you (or anyone else) thing of?
The workplace environment as it is I would not make it a point to confront someone about their homosexuality (unless the Spirit actually lead me to). But I would in no way give even an implied consent to the sin. Then if they would ask my reason for not agreeing with them it would be they who opened the door to the discussion and I would feel absolutely free to give my opinion Just my opinion.
My faith and I are not separable. Where ever I go I am a Christian 24/7. With that said it does not mean I go around sharing Jesus (i.e. gospel presentation) every second of the day. I seek to live a life that is honoring to God and when an opportunity arises I will always be willing to share. These opportunities come in many ways. Sometimes one will ask questions (of which I will always engage and give as straightforward of an answer as possible), other times a conversation opens the door to express my faith. I have no problem discussing my faith with people of different faiths, willing to listen to them and taking the opportunity to share what I believe with them as well.
The law is not as explicit in most places on this topic as many are led to believe. Even the laws on school campuses in most places isn't as bad as most think. There is still opportunity to engage, but one must do it respectfully and not be an overbearing obnoxious person. Now it is true that if you are an hourly worker and you stop working to share the gospel while on the clock you are technically stealing from your employer. I would seek to establish a time where this discussion could take place and not cause damage to my testimony by taking from my employer.