(Strip Number 4576, Original Publication Date, 4 March 1986)
Panel 1: After she complains about the irritating whining Phil made about his career somehow being destroyed by John hiring a massively unqualified idiot as a temp, John looks at his brother-in-law's Xray and reminds her of the clinic routine.
Panel 2: Since he's not aware that he's about to trip on the toy car some random child is playing with, his comment about how a good assistant is supposed to be aware of what the dentist is about to do is meant to be ironic.
Summary: This and the song I'm reminded of are only ironic because neither Lynn not Alanis Morrisette actually know what ironic means. It's just another stupid-ass coincidence. Also, it's a prime example of what's called insane troll logic. Just as Chewbacca is on Endor, John's possibly tripping over a toy car that shouldn't actually BE in his way means that Elly is allowed to make one yearn for the competence and compassion of the Three Stooges.