I am also greatly astonished; Oh brother, it's a matter of great amusement!

This couplet expresses a feeling of genuine surprise and amusement. The speaker is saying, "I too am greatly astonished," indicating a deep sense of wonder or bewilderment. Immediately following, they add, "It's a matter of great fun, brother!" This suggests that whatever is causing the surprise is not just unexpected but also highly entertaining or humorous. It's like witnessing something so unusual or delightful that it makes you exclaim both in wonder and with a chuckle. The lines capture that universal human experience of finding joy and humor in the unexpected things life throws our way. It's a lighthearted observation about life's little wonders.