The first took place during my first summer parish assignment as a seminarian (the summer of 1995). The pastor gave me my "first assignment", which was to lead a Holy Hour the following Friday evening for a group of parishioners. He basically gave me carte blanche to do what I wanted during the Holy Hour, explaining to me that, in the past, they had prayed the rosary, recited litanies, etc. When I saw the date I looked in my breviary and realized that Friday was June 1, the Feast of St. Justin. I decided we'd pray Vespers (the Church's evening prayer) with the psalms, readings, etc. proper for the feast of a martyr. I spent the day with my breviary and the copy machine, cutting and pasting, making it look perfect for that evening. I don't even remember how it went, but I remember the effort I put into it.
The second was years later, after ordination (starting in 1998). My first parish assignment had a school, and occasionally the teachers would ask me to come and speak to their classes on particular topics. The times I'm thinking about now were when I was asked to speak to the students about the Mass. When I did that, I always told the students I was going to read them what someone had written about Mass. I then read them Paragraph 1345 of the Catechism (along with my comments), which is from St. Justin's Apologia.
"On the day we call the day of the sun (Sunday), all who dwell in the city or country gather in the same place (say, a church). The memoirs of the apostles and the writings of the prophets are read, as much as time permits. When the reader has finished, he who presides over those gathered admonishes and challenges them to imitate these beautiful things (in an instruction called a 'homily'). Then we all rise together and offer prayers for ourselves . . .and for all others (intercessions), wherever they may be, so that we may be found righteous by our life and actions, and faithful to the commandments, so as to obtain eternal salvation. When the prayers are concluded we exchange the kiss (a sign of peace). Then someone brings bread and a cup of water and wine mixed together to him who presides over the brethren (an offeratory). He takes them and offers praise and glory to the Father of the universe, through the name of the Son and of the Holy Spirit and for a considerable time he gives thanks (in Greek: eucharistian) that we have been judged worthy of these gifts. When he has concluded the prayers and thanksgivings, all present give voice to an acclamation by saying: 'Amen.' When he who presides has given thanks and the people have responded, those whom we call deacons give to those present the 'eucharisted' bread, wine and water and take them to those who are absent."
When I finished, I asked them to guess when that was written. Because they recognized the order of the Mass they'd begin by saying it was written last month or a year ago. Then they'd get brave and say it was written 100 years ago or 500 years ago. Then I'd tell them that it was written in 155ad and we'd work some math into the lesson when I'd ask them to subtract 155 from the current year, and they'd find out it that we do the same things at Mass now that were done over 1800 years ago. Their faces would light up as it sank in, and that's what I remember.