I wonder whether this lent it would happen again or not: would the priest be making some remark in the homily to let us know, directly or indirectly, how useful is for evangelisation to go into the streets with the ash cross still on our foreheads? The line being, people will know that you are Christians, and if not you can start a conversation about it.
I am all up for evangelisation, standing up for our faith, and going into the streets, but perhaps Ash Wednesday is the least proper day to do this. Here goes the gospel:
“When you fast, do not do like the hypocrites, who put a sad apparence and distort they faces so that every one will see that they are fasting. Amen, I say to you, they have received their reward. But when you fast, perfume your head and wash your face¨ (Mt 6.16-17, read on Ash Wednesday)
The gospel tells us to "perfume your heads and wash your face" and not "don't show off when you are fasting", and and then we go on the streets showing off our signs of repentance. We need to share the good news of Jesus Christ everyday, but if we were to choose a day to show-off and sto pur conversation why not Easter Sunday. And everyone of us can go on the streets talking to the unbelievers that Jesus is indeed Risen.
So my suggestion is to keep the Ash Wednesday humbly.
If you are a Catholic of the Roman Rite, fasting in Ash Wednesday is "compulsory" (between the 14th and 60th birthday), but going to mass or receiving the ashes is not. If you are of the Ambrosian Rite (for instance in Milan, Italy) you don't have an Ash Wednesday and you are already in the season of lent in Monday. For the rules of fasting and abstinence see my previous post.
You may chose to do like the gospel says, and perfume your heads.