ANSWER: Apparently, there have been Catholic masses from time to time that use a clown or large puppets as part of the worship service. It appears that some liberal or even politically leftist members of the church have been occasionally using them to make ideological or doctrinal points during masses. Admittedly, the use of puppets or a clown in the liturgy of a Catholic Church mass is apparently quite rare.Through researching your question, it was discovered that the use of a clown in a variety of church or otherwise religious settings (e.g. Protestant, etc.) is not uncommon. There exists people who specialize in 'clowning ministries' whereby they help spread the gospel by performing either during worship services, when children are taught the Bible, during adult forums or other events.
The origin of some Catholics using puppets (or even a clown) to make an ideological point stems from the desire to protest against the authority of the (male) hierarchy of the church by satirizing and caricaturizing beliefs and doctrines that support those in power. For example, Catholic feminists who object to the refusal to ordain women will attack male authority in general, even when it has a Scriptural foundation with marriage and public preaching (Ephesians 5:22 - 24, 33; cf. 1Timothy 2:11 - 12).
A basic principle of church services is that they should be both reverent and orderly. The apostle Paul specifically attacked the bedlam caused by speaking in tongues out of order in the first century fellowship in Corinth (1Corinthians 14:23, 26 - 33). In my opinion, services should not be used for political purposes, for attacking a denomination's policies and so on. This is because they should mainly focus on teaching spiritual truths that transcend current conditions.
I do not see a problem, however, if puppets or a clown is ONLY used to teach children Bible stories or spiritual truths. God's word is silent on the use of such tools in such a manner. As an interesting side note, Psalm 115 praises God and condemns those who worship false deities. King David, who wrote the Psalm, gives some characteristics of idols that are surprisingly similar to that of puppets.
4. Their idols are silver and gold, the work of men's hands. 5. They have mouths, but they do not speak; they have eyes, but they do not see; 6. They have ears, but they do not hear; they have noses, but they do not smell; 7. They have hands, but they do not handle; they have feet, but they do not walk; they do not make a sound through their throat. 8. The ones who make them are like them, and so is everyone who trusts in them (Psalm 115:2 - 8, HBFV)
I hope that this answer has been helpful regarding the use of a clown or puppets in relation to church services.