Diodorus Siculus, the Greek historian, tells us that Heracles was not the boy's original name - it was Alcaeus.

After this Hera sent two serpents to destroy the babe, but the boy, instead of being terrified, gripped the neck of a serpent in each hand and strangled them both. Consequently the inhabitants of Argos, on learning of what had taken place, gave him the name Heracles because he had gained glory (kleos) by the aid of Hera, although he had formerly been called Alcaeus. Other children are given their names by their parents, this one alone gained his name by his valour.

Pseudo-Apollodorus gives a different account (a couple centuries later) and also disagrees about the birth name:

Now it came to pass that after the battle with the Minyans Hercules was driven mad through the jealousy of Hera and flung his own children, whom he had by Megara, and two children of Iphicles into the fire; wherefore he condemned himself to exile, and was purified by Thespius, and repairing to Delphi he inquired of the god where he should dwell. The Pythian priestess then first called him Hercules, for hitherto he was called Alcides. And she told him to dwell in Tiryns, serving Eurystheus for twelve years and to perform the ten labours imposed on him, and so, she said, when the tasks were accomplished, he would be immortal.

In both of these accounts, you could interpret the name as sarcastic - in the one case, because Hercules has defeated and so won glory from Hera, in the second, because he has been defeated by Hera.

As always with Ancient Greek/Roman mythology, there are different sources stating different things. Heracles was indeed born out of wedlock: Zeus did this very often, despite his wife Hera being the goddess of marriage. His mother was Alcmene, who was married. Zeus transformed into her husband, Amphitryon while he was gone, and visited her room. He made the night longer so Amphitryon wouldnt arrive while he was getting it on. Zeus seduced her and got her pregnant. When Amphitryon came back and Alcmene told him about the night with presumably him, he realized that it wasn't his child. Alcmene also got a baby with him: Iphicles.

As you could imagine, Hera was outraged when she found out. She tried to kill the baby/prevent Alcmene from giving birth in several ways, including sending witches to prevent the birth (who were tricked and sent to another room) and sending serpents to kill baby Heracles (which was, according to different sources, either stopped by Heracles by strangling them or, according to Pherecydes, Amphitryon who thought Heracles was Iphicles).

Heracles managed to survive these assassination attempts and Alcmene decided to name him Hera's glory, derived from Hera + κλεος (kleos, meaning glory), because he managed to survive even though Hera had tried (and continued to try) to make life hard for him. It was indeed sarcastic: Heracles' birth was basically Hera's failure so it was Alcmene making fun of Hera.

Sources: [Apollodorus, book 2, chapter 4] (http://www.perseus.tufts.edu/hopper/text?doc=Perseus:text:1999.01.0022:text=Library:book=2:chapter=4)

[The Life of Hercules in Myth and Legend] (http://www.ancient.eu/article/733/)

In "The Goddess and the Warrior", Marinatos investigates several Hellenic heroization myths as well as some known collective rituals. Typically, a goddess is intimately involved in the challenges necessary for mythical heroes to become immortal.

So from a naive perspective, Hera was constantly assaulting Alcaeus through no fault of his own, but within the logic of Hellenic hero cultus, she was actively giving form to his becoming divine.

Can you please clarify why you believe the meaning is humorous or sarcastic?